C# Certification Flashcards by Sean Newman

Suppose you are developing an application which stores a user’s browser history. Which collection class will help to retrieve information of the last visited page?

Last visited (LIFO= Stack)

Answer = Stack

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The following code is boxed into object o.

double d = 34.5;
object o = d;

You are asked to cast “object o” into “int”.

The object needs to be cast to double
Because it is a decimal value need to cast to float
Finally cast to int

Answer = int i = (int)(float)(double)o;

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You are developing a game that allows players to collect from 0 through 1000 coins. You are creating a method that will be used in the game. The method includes the following code. (Line numbers are included for reference only)

01 public string FormatCoins(string name, int coins)
02 {
03
04 }

The method must meet he following requirements:

Return a string that includes the player name and the number of coins
Display the number of coins without leading zeros if the number is 1 or greater
Display the number of coins as a single 0 if the number is zero

You need to ensure that the method meets the requirements. Which code segment should you insert at line 03

Format specifier D formats integer digits with optional negative sign.

Answer = string.Format($”Player {name}, collected {coins:D3} coins”);

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How do you encapsulate an array of integers into an indexer?

private int[] array;

public int this[int index]
{
  get {return array[index];}
  set { array[index] = value;}
}

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Is the following method “Display” considered to be overloaded?

class Person
{
  public void Display()
 {
 }

public int Display()
{
}
}

Overloading refers to different parameter types. The display method has different return types.

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Suppose you’re creating a class named Player. The class exposes a string property named HitSpeed. Here is the code snippet of player class.

01 class Player
02 {
03   public int HitSpeed
04   {
05     get;
06     set;
07   }
08 }

The HitSpeed property must meet the following requirements:

The value must be accessed by code within the Player class
The value must be accessed to derived classes of Player
The value must be modified only by code within the Player class.

You need to ensure that the implementation of the EmployeeType property meets the requirements. Which code segment you should replace at line 05, and 06?

protected get;

private set;

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Suppose you are developing an application. The application has two classes named Player and Person.

The Player class must meet the following requirements

It must inherit from the Person class
It must not be inheritable by other classes in the application.

Which code segment should you use?

sealed class Player : Person
{

}

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Suppose you are developing an application that includes the following code segment.

interface ICricket
{
  void Play();
}

interface IFootball
{
}

You need to implement both Play() methods in a derived class named Player that uses the Play() method of each interface.

class Player : ICricket, IFootball
{
  // Both ICricket and IFootball have play methods
  // Must be declared explicitly
  void ICricket.Play()
  {
  }
  void IFootball.Play()
  {
  }
}

Player player = new Player();
( (ICricket)player ).Play();
( (IFootball)player).Play();

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Which type cannot be instantiated?
A enum type
B static type
C class type
D System.Object type

B. Static type

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Which operator is used to get instance data inside type definition?

this

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What is the code segment for defining implicit type conversion for a Person class?

class Person
{
  public string name;
  public int age;

public static implicit operator Person(string n)
{
Person person = new Person{age=0, name=n};
return person;
}

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Which operator is used to compare types?

A) as
B) is
C) this
D) ?

B) is

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Suppose you are developing an application that saves age values in integers

int age = 22;

You are asked to provide the right code snippet for defining the extension method for age.

static class Extension
{
 public static void ExtensionMethod(this int i)
 {

}
}

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Which jump statement will you use to start the next iteration while skipping the current iteration of loop?

Continue

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You need to use null-coalescing operator to make sue “name” variable must have a value not null.

What is the right way to use null-coalescing operator in C#?

string name = n??”No Name”;

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You are developing an application that saves user’s information. The application includes the following code segment (line numbers included for reference).

01 public bool IsNull(string name)
02 {
03 return true;
04 }

You need to evaluate whether a name is null

What code segment should be inserted at line 03.

I would do this….

return string.IsNullOrWhiteSpace(name) ? false: true;

return name==null?false: true;

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Suppose you are implementing a method name “Show” that will be able to take an unlimited number of int arguments. How are you going to define its method signature.

void Show(params int[] arg)

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Which of the following methods help us to convert string type data into integers?

Select any two

A) Convert.toInt32();
B) Convert.Int32();
C) int.parse();
D) parse.int();

A) Convert.toInt32()

C) int.parse()

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What collections stores values in Key, Value pairs?

Dictionary
SortedList
HashTable

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To control how objects are compared, what interface is implemented

IComparable

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Last In, First Out data structures are represented as?

Stack

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First In, First Out structures are represented as?

Queue

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When are generic collection classes appropriate?

When all objects are of the same type

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What namespace is inherited by the following data structures?

Dictionary
List
Queue
Stack
SortedList

System.Collections.Generic

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What namespace is inherited by the following data structures? ``` ArrayList HashTable Queue Stack SortedList ```

System.Collections

Arrays inherit from what namespace?

System.Array

What object used with a DataSet is used to add, update or delete records from a database?

DataAdapter

How is a dataset populated with data?

using the DataAdapter

What is a DataSet

A disconnected resultset that contains one or more data tables

What method returns the data represented as XML

ExecuteXMLReader

What method is used to return a single value from a database such as when a query returns a Sum or Count

ExecuteScalar

What object is a read-only, forward-only cursor connected to the database?

DBDataReader

What method is used to execute non-result returning queries such as Insert, Update or Delete

ExecuteNonQuery

What object is used to call a stored procedure or execute a dynamic SQL statement?

The Command object

What is ADO.Net?

A set of classes used to execute commands on a database

An ORM tool that masks the syntax for using ADO.Net to communicate with a database is referred to as?

Entity Framework

Classes are representative of what within Entity Framework Model

objects in the database

Within the Entity Framework Model, stored procedures are represented as what?

Methods

How are parameters passed by WCF Data Services to query a database?

By passing the parameters within the URL query string

What data formats are returned by WCF Data Services?

OData Adam | JSON

What protocol is used by WCF Data Services?

OData

What purpose does the await command serve?

Kicks off the method and returns processing to the calling method until the method completes

The async keyword must modify what in order to use the await keyword?

The method signature

In C# 5.0 and later, what keywords are used to perform asynchronous operations?

asynch & await

What classes are used to read and write string data

StringWriter | StringReader

Name three methods used by StreamReader to get the contents of a file.

Character by Character Line by Line Entire File at once

What is the default character encoding for StreamReader and StreamWriter

UTF-8

What classes are used for reading and writing characters by using an encoded value to convert the characters to and from bytes?

StreamReader | StreamWriter

What classes are used for reading or writing binary values?

BinaryReader | BinaryWriter

What object is used to represent the contents of a file in memory and can be used to write data or read data from a file.

Stream

What objects are used to determine properties of a file and also performs operations on a file

File and FileInfo

In LINQ, what is an outer sequence?

The sequence calling the Join method

A feature of LINQ that uses extension methods on types that implement the IEnumerable or IQueryable interface to query the data is a ..?

Method based query.

LINQ statements executed in a where clause for a query expression is called it's..?

Predicate

LINQ statements that select a subset of properties from a type that creates a new anonymous type is referred to as ?

Projection

A feautre of LINQ that enables you to query any type that implements the IEnumerable or IQueryable interface is called?

Query expression

A set of features that extends query capabilities to C# is called?

Language Integrated Query or LINQ

In LINQ, what is an inner sequence?

When using a method based join, the sequence passed to the join as a parameter.

A variable that has its type determined by the expression on the right side of the initialization statement and using the keyword var is .. .?

Implicitly typed

What operator is the"goes to" or "such that" operator?

=> | Used primarily in lambda expressions

Execution of a LINQ query is deferred until the result is enumerated. This is referred to as ?

Deferred execution

Define a composite key

Contains multple properties that are needed to complete a join.

A type created with read-only properties without having to write the code to declare the class is referred to as an....?

Anonymous type

What class is used in a LINQ to XML query to return the result of a query in XML?

XElement

What LINQ method allows you to return a distinct list of elements from a sequence?

Distinct

What LINQ method allows you to return a limited number of elements from a sequence.

Take

What LINQ method allows you to skip a specific number of elements in a sequence?

Skip

In LINQ, how are two sequences concatenated?

Concat

When using method based LINQ queries, how are out joins formed?

GroupJoin

In LINQ, what is the purpose of the SelectMany method?

To flatten two sequences into one result, similar to join.

Which LINQ query uses lambda expressions as parameters to methods?

Method based queries

What is the difference between method based queries and query expressions?

Syntax, no functional difference.

In LINQ, a group by clause returns what data type?

IGrouping

How is a LINQ composit key formed?

By specifying an anonymous type in the join clause

In LINQ, how are outer joins formed?

1) Include an INTO clause in your join | 2) Call the Default ifEmpty to set properties when no match is found.

What keyword is used to join properties in LINQ?

Equals

Define projection

Creating a custom type in a select clause of a query expression using a limited number of properties from the original object.

What query expression clause is used to sort the results on one or more properties?

OrderBy

How are multiple where clauses implemented using LINQ?

By using the && operator

Define the predicate in LINQ

All code contained within the Where clause

How are joins evaluated in LINQ queries?

Joins are always equivalence based

How is the execution of a LINQ query forced?

By using any of the aggregate functions or populating a list or array using toList() or toArray()

When does execution of a LINQ query occur?

When the result is enumerated

Define a LINQ clause

A query expression containing Select, GroupBy, Where or joins

By convention, the results of a LINQ query are stored where?

To a variable of type var, allowing the result to be implicitly typed.

What object can be queried by LINQ?

Any object that implements IEnumerable or IQueryable

Define the correct order of keywords for a LINQ query expression.

from... where ... select ...

Define a statement that returns the count of all even numbers

``` var count = myNumbers.Where(i => i %2 == 0) .Count() ```

Define a statement that groups a sequence by the State property

var states = myStates.GroupBy(s => s.name);

Define a statement that creates an anonymous type

.Select( new {h.city, h.state})

What two keywords must you use in a join clause to create an outer join?

into | DefaultIfEmpty

Define a clause that joins two sequences on the stateId property

on e.stateId equals s.stateId

Define a join clause that uses a composite key

on new {City = e.City, State = e.State} equals new {City = h.City, State = h.State}

Define a LINQ clause that orders by state and then by city

Orderby h.state, h.city

Define a WHERE clause that returns all integers between 10 and 20

Where i >= 10 && i <= 20

Define the extension LINQ method used to find the first item in a sequence

First or Take

Define how to find the minimum value in a sequence

(from i in myArray | selecti).Min()

Given: var result = from i in my Array order by i select i; ``` foreach(int i in result) { // Do something } ``` Where is the LINQ query executed?

When enumerating the foreach statement

# Define a WHERE clause that selects all integers in a myList object that are even number given from i in myList

Where i % 2 == 0;

Name two methods of performing customized serialization

Attributes (the preferred method) | Implement Iserializable

What class is used to perform binary serialization.

BinaryFormatter

XML serialization is performed by what class?

XMLSerializer

What class is used to perform JSON serialization

DataContractJsonSerializer

What is serialization?

The process of transforming an objects data to persisted storage or to transfer the object from one domain to another

A set of classes in the .NET framework that enables you to convert to a database, retrieve data, execute stored procedures, add, update, or delete records in a table called?

ADO.NET

What is the object relationship mapping tool that provides a graphical interface that generates code to perform operations against a db using ADO?

ADO.NET Entity Framework

The most basic type used to store a set of data is called?

Array

What is the role of the keyword async?

Indicates that the method, lambda expression, or anonymous method is asynchronous

What keyword suspends the execution of a method until the awaited task completes?

await

The process of converting a reference type to a value type is called?

unboxing

What is boxing?

The process of converting a value type to a reference type

What is a collection?

A generic term encompassing lists, dictionaries, queues, stacks, hash tables and other objects that contain sets of data.

The object in ADO.NET that allows you to open and execute commands against a database is called?

A connection object.

What is the IComparable interface?

Implements an interface that can be sorted when used in a collection or array.

A method that is used when referencing an element in an array or collection by using square brackets[] and it's index is called?

indexer

What is JSON?

JavaScript Object Notation A lightweight data-interchange format

A computer software term for tools that convert data between type systems using an object oriented programming language is called?

ORM Object Relational Mapping

The XML representation of data returned from an OData query is called?

OData ATOM

What is OData?

Open Data Protocoal A web protocol for querying and updating data over the intranet or internet

Creating a new copy of an object that copies all value types and copies object references for reference types is called a ?

shallow copy

The process of converting an object into a stream of bytes that can be stored or transmitted is called?

serialization

Define stream.

An abstract class that provides a generic view of a sequence of bytes.

What is a T4 template?

A file that contains text blocks and control statements that enable you to generate a code file.

What enables you to use OData to expose and consume data over the web or intranet?

WCF Data Services WCF=(Windows Communication Foundation)

You are working with a large group of family objects. You need to remove all duplicates and then group them by last name. Which collections should you use?

List to hold the original objects Dictionary to remove duplicates and create key of last names.

You are using a queue and you want to add a new item. Which method do you use?

Enqueue

You want to store a group of orders and make sure that a user can easily select an order by it's order number. Which collection do you use?

Dictionary

What must be implemented when creating custom collections?

Both IEnumerable and IEnumerable

What collection stores values in memory as a last-in-last-out structure?

Stack, Stack

What collection stores value in memory as a first-in-first-out structure?

Queue, Queue

What collection stores unique items and offer set operations?

HashSet

What is a dictionary?

A collection that stores and accesses items via key/value pairs.

What is the most used collection?

List, List

Define an Array

The most basic collection type which is constrained by a fixed size

When given the opportunity to use the generic or non-generic collection, which is generally preferred?

Always use generic where possible.

You want to serialize some data to XML, and you need to make sure that a certain property is NOT serialized. Which attribute should you use?

XMLIgnore

You are serializing some sensitive data to a binary format. What should you use?

BinaryFormatter to put the data in binary format. ISerializable to protect sensitive data.

JSON text formatted files are created in .NET using what class?

DataContractJsonSerializer

You need to store a large amount of data and you want to do this in the most optimal way. What serializer should you use?

BinaryFormatter

WCF serialization is performed using what class?

DataContractJsonSerializer

How is binary serialization performed in .NET?

Using the BinaryFormatter class

How is the XMLSerializer configured?

Through the use of attributes.

What class handles XML serializtion?

XMLSerializer

What is deserialization

Takes a series of bytes or a flat file and transforms it to an object

What is serialization?

The process of transforming an object to a flat file or series of bytes

Given query ``` var query = from p in myContext.Products where p.price < 50 select p; int numberOfItems = query.Count(); var products = query.ToList(); ``` How can you improve performance?

Use paging to limit the number of items retrieved And Avoid hitting the database multiple times

You are trying to use a LINQ query but receiving a compile error that the Where method cannot be found. What steps should you take?

1. verify using System.Linq | 2. Validate the datatype implements IEnumerable, IEnumerable

You have a list of data you want to filter the dates to the current year and then select the highest date. Create the query.

DateTime result = dates.Where( d => d.Year == DateTime.Now.Year) .OrderByDescending( d=>d) .FirstOrDefault();

When are LINQ queries executed?

Not until they are first iterated, known as deferred execution.

What is the primary function of LINQ?

To provide a uniform way of writing queries against multiple data stores.

Which ADO.NET command objects's property would you use when a query returns the sum of a column in a table?

ExecuteScalar

Which property of an ADO.NET DataAdapter is used to insert records in a database?

InsertCommand

Which method of a DataAdapter is used to populate a DataSet?

Fill

Which ADO.NET object is fully traversable cursor and is disconnected from the database?

DataTable

Which ADO.NET command object's property would you use when a query returns the sum of a column in a table?

ExecuteScalar

Which ADO.NET object is a forward-only cursor and is connected to the database while the cursor is open?

DBDataReader

using ADO.NET Entity Framework how is a record updated in the database?

Category category = db.Categories.First( c => c.CategoryName = "alcohol"); category. Description = "Happy Please"; db. SaveCjhanges();

Using ADO.NET Entity Framework, how is a record added to the database?

``` using(NorthwindsEntitities db = new NorthwindEntities()) { Category category = new Category() { category = "Alcohol", description = "beverage" } ``` db.Categories.Add(category); db.SaveChanges(); }

How are stored procedures represented in the ADO.NET Entity Framework?

A method is added to the model that is the same name as the stored procedure.

When using the ADO.NET Entity Framework you create a model that represents the object in the databases. What class does the model inherit from?

DBContext

Which command object's method would you use to execute a query that returns only one row and one column?

ExecuteScalar

Which command object's method would you use to execute a query that does not return any results?

ExecuteNonQuery

Which properties of an ADO.NET command object must you set to execute a stored procedure?

CommandType CommandText Parameters

Which ADO.NET object is used to connect to a database?

Connection

Which collection would you use if you need to quickly find an element by its key rather than it's index?

Dictionary or SortedList

Which collection would you use if you need to process the items in the collection on a last-in, first-out order?

Stack, Stack

Which collection would you use if you need to process the items in the collection on first-in, first-out order?

Queue, Queue

If you create a custom class that is going to be used as elements in a List object and you want to use the Sort method of the List object to sort the elements in the array, what steps must you take?

1. Inherit from IComparable | 2. Implement CompareTo()

Which type should you use to store objects of different types but do no know how many elements you need at the time of creation?

ArrayList

Which object does the variable mySet inherit from? int[] mySet = new int[5];

System.Array

Custom collections must inherit from which base class?

CollectionBase

What is SSL?

Secure Socket Layer is a cryptographic protocol used for secure communication over the internet.

Define secured hash algorithm

SHA is a family of cryptographic algorithms used to calculate hashes published by NIST

What is the infrastructure required to handle digital certificates?

Public Key Infrastructure (PKI)

A family of cryptographic algorithms used to provide data integrity and authenticity is called?

Message Authentication Code (MAC)

What is the Just In Time (JIT) compiler?

A component of the .NET that transforms the IL into binary code that can be run on the target platform.

The result of compiling a .NET application from source code is called the?

Intermediate Language (IL)

A data array used by the encryption algorithm to encrypt the first data block is referred to as the?

Initialization Vector (IV)

Describe hashing.

Used to map data structures of variable length to fixed size data structures.

A data structure that holds items that share the same hash value is called?

Hash Bucket

What is the Global Assembly Cache?

The GAC is a machine-wide code cache

The process of decoding previously encrypted data so that it can be used by your application is?

Decryption

The process of encoding data so that it cannot be read by an unauthorized person is called?

Encryption

The practice and study of techniques for secure communication is called?

Cryptography

A list of digital certificates that have been revoked for various reasons is referred to as?

Certificate Revocation List (CRL)

Define the CLR

The Common Language Runtime is the component of the .NET Framework responsible for running .NET applications and managing the running environment.

Define Certificate Stores

A special storage location on your computer, used to store encryption certificates

What entity issues digital certificates?

Certificate Authority (CA)

Define asymmetric encryption

A criptographic algorithm that uses two complimentary keys. One for encryption and one for decryption.

What is an assembly?

An assembly is the unit of reuse, deployment, versioning and security.

You need to process a large number of XML files ina scheduled service to extract some data. Which class should you use?

Because data is only being extracted, use XmlReader

You are planning to build an application that will use an object-oriented design. It will be used by multiple users at a time. Which technology should you use?

An ORM such as Entity Framework

You want to update a specific row in the database. What commands are required?

1. SqlConnection to establish connection to database | 2. SqlCommand to execute the query

Name the four classes used to manipulate XML.

XmlReader XmlWriter XPathNavigator XmlDocument

Why should you use parameterized queries when performing CRUD operations?

To avoid Sql injection

Under ADO.NET, how are connections made to the database?

Using the DBConnection object

What is ADO.NET?

A provider model that enables you to connect to different types of databases.

You are writing an application that will be deployed to western countries. It outputs user activity to a text file. Which encoding should you use?

UTF-8

You have built a complex calculation algorithm. It takes quite some time to complete and you want to make sure that your application remains responsive, what do you do?

Task.Run() The process will run on a background thread

You are creating a new file to store some log data. Each time a new log entry is necessary, you write a string to the file. Which method should you use?

File.AppendText

What namespace supports WebRequest and WebResponse?

System.Net

What classes are used for performing network requests?

WebRequest | WebResponse

What class implementation is used for dealing with files, network operations and other types of IO

Stream

Define streams

An abstract method for working with a series of bytes

What methods are available to create and parse file paths?

static Path class

What methods are provided to work with files?

File | FileInfo

How are folders manipulated programmatically?

Directory | DirectoryInfo

How are drives manipulated programmatically?

Drive | DriveInfo

Write code to decrypt an array called encryptedData that was encrypted by the current user and without using entropy

ProtectedData.Unprotect( encryptedData, null, DataProtectionScope.CurrentUser);

What is a strong name assembly?

A signed assembly

How can you deploy a private assembly?

By copying the file to the bin folder or Adding a reference to the assembly via Visual Studio

How can you deploy a strong named assembly?

``` Run gacutil.exe or copy file to bin folder or create an installer ```

Describe the components of a strong named assembly

``` Name Version Public Key Token Culture Processing Architecture ```

Write a code snippet to encrypt an array called userData that can be decrypted by anyone logged in on the current machine without using any entropy.

ProtectedData.Protect(userData, null, DataProtectionScope.LocalMachine);

Write a code snippet to calculate the secure hash of a byte array called userData using the SHA algorithm

sha.ComputeHash(userData);

You are a developer at company xyz. You have been asked to implement a method to handle password encryption without offering the possibility to restore the password What algorithm fits the requirement?

Hashing algorithm

You are a developer at company xyz. You have been asked to implement a method to safely send data to another machine. What kind of algorithm best fits the requirement?

Asymmetric algorithm

You are a developer at company xyz. You have been asked to implement a method to safely save and restore data on the local machine. What kind of algorithm best fits the requirements?

Symmetric algorithm.

When is a MAC algorithm recommended?

To ensure both authenticity and integrity is required

When is the hashing algorithm recommended?

When data integrity is the only requirement

When is asymmetric encryption recommended?

If you do not have a way to send data securely

When is symmetric encryption the best option?

IF you need to encrypt data locally or you have a secure way to distribute the encryption key.

How is the encryptor/decryptor used?

Directly, using TransformFinalBlock or sending to CryptoStream

How is symmetric encryption instantiated?

By calling CreateEncryptor CreateDecryptor

What is required to perform symmetric encryption?

An initialization vector (IV) used to encryp the first block of data.

Define symmetric encryption

Encryption based on a shared secret

How many keys are used in asymmetric encryption?

Two 1. Private key 2. Public key

Define asymmetric encryption

Based on a pair of complimentary keys. Data encrypted by one key can be decrypted by the other.

Write a regular expression that matches license plate values that must include three uppercase letters, followed by a space and three digits, or three digits followed by a space and three uppercase letters.

(^d{3} [A-Z] {3}$) | (^[A-Z]{3} \d{3}$)

Write a regular expression that matches a username that must include between 6 and 16 letters, numbers and underscores

^[a-zA-Z0-9_]{6,16}$

Write a regular expression matching the social security number format ###-##-#### where # is any digit.

^\d{3}-\d{2}-\d{4}$

What method returns true if a regular expression matches a string?

Regex.IsMatch

What is the best use of performance counters?

To determine how often a particular operation is occurring on the system as a whole.

True or False Whan an assertion fails in debug builds, the Debug.Assert method allows you halt, debug the program or continue running?

True

True or False The program must continue running even if a Debug.Assert method stops the program

True

True or False The Debug.Assert method is ignored in release builds

True

What builds define the TRACE symbol?

Debug and Release

What builds define the Debug symbol

Debug

How can you prevent Visual Studio from creating a .pdb file?

Setting the value of PDB file type to "None"

What file is required to debug a compiled executable?

.pdb file

What statements are used to trace or log a program's execution?

DEBUG and TRACE

The process of making the program record key events in a log file is referred to as?

logging

The process of instrumenting a program to track what is doing is referred to as ?

Tracing

What method would you use to investigate bottlenecks in a program?

Use an automatic profiler

What statement can be used to validate data as it moves through a program?

Debug.Assert

How are preprocessor symbols disabled?

#UNDEF

What processor directives define preprocessor symbols?

#DEFINE

How can you determine what code is included in a program?

``` By using directives #if #elif #else #endif ```

What is the purpose of the #line directive?

To change the line number or name of file reported as errors

How are custom warnings and/or errors added to the error list?

by using #warning or #error

What is the syntax to create collapsible code regions?

``` #region .. #endregion ```

What is the syntax to disable a warning?

#pragma warning disable

What is the syntax to restore a warning?

#pragma warning restore

Where is the predefined constant TRACE defined?

In the debug and release builds

Where is the predefined constant DEBUG defined?

In the debug builds

Calls to DEBUG and TRACE are ignored if?

Both DEBUG and TRACE are not defined

Useful DEBUG and TRACE methods include?

``` Assert Fail Flush Indent Unindent Write WriteIf WriteLine WriteLineIf ```

When adding standard listeners to Debug and Trace objects, where are messages written to?

1. Output window 2. Event logs 3. Text files

What file is used to debug a compiled executable?

.pdb

What directives are used to implement tracing?

DEBUG and TRACE

Instrumenting a program to trace it's progress is known as?

Tracing

Name the methods to support logging

1. Writing to a text file 2. Using DEBUG and TRACE with a listener to write to a text file 3. Writing to an event log

The recording of key events is known as?

logging

What methods are used to support profiling?

1. Using a profiler 2. Instrumenting code by hand 3. Performance counters

Gathering information about a program to study characteristics such as speed and memory usage is referred to as?

Profiling

A test on data ot see if the data makes sense is referred to as a ?

sanity check

What is tracing?

The process of instrumenting a program so that you can track what it is doing

What is a regular expression?

An expression in regular expression language that defines a pattern to match.

What is profiling?

The process of instrumenting a program to study it's speed, memory, disk usage, or other performance characteristics.

An automated tool that gathers performance data for a program by it's code or by sampling is referred to as?

a profiler.

What is a performance counter?

A system-wide counter used to track some type of activity on the computer.

A regular expression used for matching parts of a string is called?

a pattern

What is logging?

The process of instrumenting a program so it records key events?

Adding features to a program to study the program itself is called?

instrumenting

Options set in a regular expression using the syntax | (?imasx) are referred to as ?

inline options

A sequence of characters that have special meaning in a regular expression is referred to as a ?

escape sequence

Define data validation

Program code that verifies that a data value makes sense

A predefined symbol created by Visual Studio that you can use with #if, #elif, #else and #endif directives to determine what code is in the program?

Conditional Compilation Constant

A regular expression construction that represents a set of characters to match is?

character class

A piece of code that makes a particular claim about data and throws an exception if that claim is false is called?

An assertion

What method is used to create assertions?

System.Diagnostics.Debug.Assert

Given the following: MyClass myClass = new MyClass(); MethodInfo myMethod = typeof(MyClass).GetMethod("Multiply"); using reflection, execute the method and pass in two parameters.

myMethod.Invoke(myClass, | new object[]{4,5});

Which method of the MethodInfo class can be used to execute the method using reflection?

Invoke

Assume myClass is an instance of a class. Create a statement that returns a private instance field called "myPrivateInstance" using reflection.

MyClass.GetType().GetField("myPrivateField", BindingFlags.NonPublic | BindingFlags.Instance);

Which property of the Type class can you use to determine the number of dimensions in an array?

GetArrayRank

Which class in the System.Reflection namespace is used to represent a field defined in a class?

FieldInfo

Using reflection, how an you determine if a class is public or private?

Create an instance of the Type class using typeof() and then examine the IsPublic propery of the Type variable

Which class would you create if you wanted to determine all properties contained in a class using reflection?

Type

Create an instance of a DataTable using reflection

myAssembly.CreateInstance("System.Data.DataTable");

Which method should you call if you want .NET Framework to look in the load-from context?

LoadFrom

Which method should you call if you want the .NET Framework to look in the load-context to load an Assembly?

Load

Define the syntax to load an assembly

1. Assembly.Load("System.Data", Version=4.0.0.0, Culture = neutral, PublicKeyToken=b77a5c561934e089); 2. Assembly.LoadFrom(@"c:\myProject\Project1.dll"); 3. Assembly.LoadFile(@"c:\myProject\Project1.dll"); 4. Assembly.ReflectionOnlyLoad("System.Data", Version=4.0.0.0, Culture = Neutral, PublicKeyToken=b77a5c561934e089);

Which method of the Assembly class returns an instance of the current assembly?

GetExecutingAssembly

Which property of the Assembly class returns the name of the assembly?

FullName

Which method of the Assembly class allows you to get all the public types defined in the assembly?

GetExportedTypes

Which class in the System.Reflection namespace would you use if you want to determine all the classes contained in the .dll file?

Assembly

You are asked to create a custom attribute that has a single property, called version, that allows the caller to determine the version of the method. Which code creates the attribute?

``` class MyCustomAttribute:System.Attribute { public string Version{get; set;} } ```

You are a developer for a finance department and are building a method that uses reflection to get a reference to the type of object passed as a parameter. Which syntax is used to determine object type?

Type myType = myParameter.GetType();

You are consulting for a company called Contoso and are taking over an application that was built by a third party. How can you figure out which .dll files are being referenced?

1. Create an instance of the assembly class 2. Load the assembly 3. Call the GetReferencedAssemblies method

What code creates a lambda expression returning the squares of an integer?

x => x * x;

You are given an assignment to create a code generator to automate the task of creating repetitive code. Which namespace contains the types needed to generate code?

System.CodeDom

The process that permits parameter types that are less derived than the delegate type?

Contravariance

The process that enables you to have a method with a more derived return type than the delegate return type is ?

Covariance

The => symbol in a lambda expression is referred to as?

goes to or such that

What is a delegate?

A type that references a method

Shorthand syntax for anonymous functions are referred to as?

lambda expressions

What class generates the class file in either C#, VB or JScript?

System.CodeDom.CodeDomProvider

In the codeDom, what class is the top level class?

System.CodeDom.CodeCompileUnit

What is the CodeDom?

Code Document Object Model As set of classes that enables you to create code generators

Custom attributes inherit from what class?

System.Attribute

How is an attribute declared?

By decorating with square brackets []

What enables you to create metadata for a class, property or method?

Attributes

What method returns a PropertyInfo object and enables you to set or get a property's value?

Type.GetProperty

What does System.Type represent?

A class, interface, array, value type, enumeration, parameter, generic type definition and open or closed generic types.

What method creates an instance of a type?

Assembly.CreateInstance

What method loads the assembly but does not enable execution?

Assembly.ReflectionOnlyLoad

What method loads an assembly into memory and enables you to execute code?

Assembly.Load

What class is used to examine the types within an .exe or .dll file?

System.Reflection.Assembly

Name the two ways to get a reference to the Type object

typeof() and .GetType()

What is a type?

A class, interface, array, value type, enumeration, parameter, generic type definition, open or closed generic type.

The class, porperty or method that contains metadata defined by an attribute is called the...?

Target

A lamdba expression containing more than one statement in the body of the expression is referred to as a ...?

statement lambda

What is reflection?

Provides lasses that can be used to read metadata or dynamically invoke behavior from a type?

Describe probing

The process of looking in the GAC, the host assembly store, the folder of the executing assembly, or the private bin folder of the executing assembly to find an assembly

A file, typically a .dll or .exe that composes an assembly is referred to as a ..?

module

When loading an assembly using reflection, what context contains the assemblies located inthe path passed into LoadFrom method.

load-from context

When loading an assembly during reflection, what context contains the assemblies found by probing

load context

Define a lambda expression

Shorthand syntax for an anonymous method that can be associated with a delegate or expression tree.

A variable in a class or structure is referred to as a ..?

field

Code in a tree-like structure where each node is an expression is referred to as a...?

Expression tree

What is an expression lambda?

An expression that contains one statement for the body.

What type is a reference to a method?

delegate

Define covariance

Enables you to have a method with a more derived return type than the delegates return type

Define contravariance

Permits parameter types that are less derived than the delegates parameter types.

When loading an assembly using reflection, where does reflection search for the assembly?

in the context

Define the CodeDOM

Code Document Object Model Enables the developer to generate code in multiple languages at run time based on single code set.

What enables you to associate metadata with assemblies, types, methods, properties...?

attributes

A compiled piee of code in a .dll or .exe is referred to as a ?

assembly

What method enables you to associate a block of code with a delegate without a method signature?

anonymous methods

If during Garbage Collection a program has no path of references that access the object, the object is ?

unreachable

Resources that are not under the control of the CLR are known as?

unmanaged resources

A base or parent class is also known as?

the superclass

The process of deriving a subclass from a base class through inheritance is referred to as ?

subclassing

What is a subclass?

A derived class

Classes that have the same parent class are referred to?

sibling class

A copy of an object where reference fields refer to the same objects as the original is a ..?

shallow clone

If the program has a path of references that allow access to the object than it is?

reachable

A base, or superclass is known as the?

parent class

Because you cannot direct when the GC will call an objects Finalize method, the process is referred to as ?

Nondeterministic finalization

Allowing a child class to have more than one parent class?

multiple inheritance (not allowed in C#)

Resources that are under the control of the CLR are?

managed resoources

Using an interface to require a class to provide certain features much as inheritance does is referred to as ?

Interface inheritance

What does it mean to inherit?

A derived class inherits the properties, methods, events and other code from the base class.

The process that executes periodically to reclaim memory that is no longer accessible to the program

Garbage Collection (GC)

What is Garbage Collection?

The process of running the Garbage Collector to reclaim memory no longer available to the program

A queue through with object with finalizers must pass before being destroyed is called the ?

finalization queue

What is finalization?

The process of the garbage collection calling the objects Finalize method.

What is a destructor?

A method with no return type and the class name preceded by the ~ symbol

A class's children, as well as their children are referred to as?

descendant class

The creation of one class based on another through inheritance is referred to ?

deriving a class

A copy of an object where reference fields refer to new instances of objects?

deep clone

A virtual machine that manages C# ( and other .NET) programs is the ?

Common Language Runtime (CLR)

A class derived from a parent class is referred to as the ?

child class

A class from which another class is derived via inheritance is referred to as the ?

base class

A class parent is referred to as an ?

ancestor class

What is the purpose of tying the using statement to the Dispose method?

The program automatically calls the Dispose method and limits the object scope to the block.

Why does the Dispose method call GC.SuppressFinalize?

Prevents the garbage collector from running objects destructor and keeps the object out of the finalization queue.

What resources are freed by a destructor?

unmanaged resources

What resources should be freed in a Dispose method?

manage and unmanaged resources

Yes or No Can a dispose method be executed more than once?

Yes

Yes or No For classes with only unmanaged resources, should IDisposable be implemented?

Yes and it needs to implement a destructor

Yes or No For classes with managed resources, should IDisposable be implemented?

Yes, but a destructor is not required

Yes or No Do classes with no managed or unmanaged resource require an implementation of IDisposable?

No A destructor is not required

What methods are destructors converted to by the compiler?

Finalize

Yes or No | Can access modifiers or parameters be defined on a destructor?

True or False Destructors can be inherited or overloaded?

False

How many destructors can be assigned to a class?

No more than one

True or False Destructors may be defined in structs and classes

False Destructors are only defined in classes

How are objects added to an IEnumerator result

yield return

Which interface returns an object used for moving through lists of objects?

IEnumerable

What method of ICloneable returns a copy of the object?

Clone

What interface provides an equal method to determine if two objects are equal to one another?

IEquatable

What interface provides a Compare method to compare two objects to determine their ordering?

IComparer

What method from IComparable is provided to determine the order of objects?

CompareTo

When code can use either a class instance or interface instance to access the interface, then the interface was implemented how?

implict

Define interface inheritance

The act of implementing an interface

If a class implements an inteface explicitly, how is the explicit reference acessed?

It must use an interface instance

How many classes and interfaces can a class inherit?

``` one class any number of interfaces ```

Buy convention, interface names begin with what letter?

I (IEnumerable, etc)

True or False If a parent class has constructors, the child class constructor must invoke them directly or indirectly

True

True or False At most, a constructor can invoke one base class or one same class constructor.

True

Use the this keyword to create a snippet to make a constructor invoke another constructor in the same class

``` public class ClassName { public object PropertyName{get; set;} public object PropertyName2{get; set;} public ClassName(object x) { propertyName = x; } public ClassName(object x, object y) : this( PropertyName(x)) { propertyName2 = y; } ```

Use the base keyword to make a constructor to invoke the parent constructor

``` public class Child :Parent { public Child(obj x, obj y) : base(x, y) { // Do something } } ```

Does C# support multiple inheritance?

If a class has unmanaged resources and no managed resources should IDisposable provide a destructor?

Yes Implement IDisposable and provide a destructor

If a class has managed resources and no unmanaged resources should IDisposable provide a destructor?

No Implement IDisposabel but provide no destructor

If a class implements IDisposable, what three steps should be completed by the Dispose method?

1. Free the managed resources 2. Free unmanaged resources 3. Call GC.SuppressFinalize

True or False Destructors are inherited?

False

True or False Before destroying an object, the Garbage Collector (GC) calls it's Dispose method?

False The GC calls the Finalize method

The IEnumerable and IEnumerator interfaces provide what methods to move through a list of objects?

MoveNext and Reset

True or False A class can inherit from at most one class and implement any number of interfaces

True

Suppose you want to sort the recipe class by any of the properties; main ingredients, total time or cost per person. Which interface would probably be most useful?

IComparer

Suppose you want to make a recipe class to store cooking recipes and you want to sort the recipes by the main ingredient property. Which interface would be most useful?

IComparable

Is code reuse a goal of interface design?

No The goals are 1. Simulating multiple inheritance 2. Treating unrelated objects in uniform way 3. Polymorphism

Suppose the Houseboa class implements the IHouse interface implicitly and the IBoat interface explicitly. Can the code use Houseboat object to access the IBoat members?

Suppose you have defined the House and Boat classes and you want to make a HouseBoat class that inherits from House and Boat. Can you inherit from both House and Boat?

No C# classes support single inheritance

If the base statement is declared first, can the constructor use a this statement and a base statement?

Does the use of the base keyword allow a constructor to invoke a different constructor in the same class?

You are working on a global application with lots of users. The operartion staff requests information on how many user logons per second are occurring. What should you do?

Implement a performance counter using the RateOfCountsPerSecond64 type

Users are reporting errors in your application, and you want to configure your application to output more trace data. Which configuration setting should you use?

Switch The switch value determines which trace events should be handled.

You are using the TraceSource class to trace data when an order cannot be submitted to the database and you are going to perform a retry. Which TraceEventType should you use?

Error Alerts that something is wrong that needs to be recovered.

When experience performance problems, what can you do to isolate and resolve root cause?

Profile the application

What classes are used to log and trace messages?

DEBUG and TRACE

When should logging and tracing be implemented?

from the beginning of the project

You are using custom code generation to insert security checks into your classes. When an exception occurs, you're having trouble finding the correct line in your source code. What should you do?

Use the #line directive with the correct line numbers in your generated code to restoring the original line numbers

You are debugging an application for a web shop and are inspecting a lot of Order classes. What can you do to make your debugging easier?

Use the DebuggerDisplayAttribute on the Order class

You are ready to deploy your code to a production server. Which configuration do you deploy?

Release configuration

What build outputs code that can be deployed to production?

Release build

What tools are provided to give extra instructions to the compiler.

compile directives

What type of build outputs a nonoptimized version of the code that contains extra instruction to help debugging?

Debug build

The compiler can be configured in Visual Studio through use of what tool?

Build configurations

You want to deploy an assembly to a shared location on the intranet. Which steps should you take?

Strongly name the assembly Use the codebase configuration element in the applications that use the assembly

You are building an assembly that will be used by a couple server applications. You want to move the update process of this assembly as smooth as possible. Which steps should you take?

1. Deploy the assembly to the GAC | 2. Strongly name the assembly

You are building a stong-named assembly and you want to reference a regular assembly to resuse some code you built. What steps need to be taken?

You need to sign the other assembly before using it.

How are applications bound to the assemblies they were developed with?

by using versioning

What is a WinMD assembly?

A special type of assembly used by WinRT to map non-native languages the native WinRT components.

Signed assemblies may be placed where?

inside the Global Assembly Cache (GAC)

To prevent tampering what may be done to an assembly?

Strongly signed

A compiled unit of code that contains metadata is referred to as an ?

assembly

You need to send sensitive data to another party and you want to make sure that no other party tampers with the data. Which method do you use?

X509Certificate2.SignHash

You need to encrypt a large amount of data. Which algorithm should yoour use?

AESManaged

Boba and Alice are using an asymmetric algorithm to exchange data. Which key should they send to the other party to make this possible?

Bob sends Alice his public key | Alice sends Bob her public key

What is the method used to verify the authenticity of an author?

Digital Certificates

What process is used to retrict the resources and operations an application can access and execute.

CAS

What is the purpose of System.Security.SecureString?

Maintains sensitive string data in memory

What is hashing?

The process of converting a large amount of data to a smaller hash code

What algorithm uses a public and private key that are mathematically linked?

Asymmetric algorithm

What algorithm uses the same key to encrypt and decrypt data?

Symmetric algorithm

You need to validate an XML file. What do you use?

XML Schema Definition (XSD)

You are working on a globalized web application. You need to parse a text field where the user enters an amount of money. What method do you use?

You need to specify the number styles. Currency and culture that the user is using. decimal.TryParse(value, NumberStyles.Currency, UICulture);

A user needs to enter a DateTime in a text field. You need to parse value in code. Which method do you use?

DateTime.Parse

When receiving JSON and XML files, it is important to validate them using what built-in types.

JavascriptSerializer and XMLSchemas

What can be used to match input against a specified pattern or replace specified characters with other values?

regular expressions

What functions are used to convert between types?

1. Parse 2. TryParse 3. Convert

Where is data integrity managed?

By your application and your data store

Why is validating application input important?

To protect your application from mistakes and/or attacks

What steps are required to make sure data is not modified while transferred?

1. Calculate the cryptographic hash 2. Send the hash with the data for validation by the receiving party.

Name two commonly used hashing algorithms?

SHA256 | SHA512

Mapping binary data of a variable length to a fixed size binary data is called?

hashing

How are asymmetric private keys secured?

By using certificates or by using Crypto Service Providers containers

How are symmetric keys exchanged?

Using asymmetric algorithms

Name the four parts of an assembly version

Major Minor Build Revision

Name the five parts of a strong name assembly

``` Friendly name Version Culture Public Key Token Processor Architecture ```

What is an assembly called that has been digitally signed?

strong named assembly

Can more than one version of an assembly be deployed to the GAC?

Yes Several versions of the same assembly can be deployed on the GAC at the same time.

What type of assemblies can be deployed to the GAC?

only strong named assemblies

What is the GAC?

Global Access Cache A repository to share .NET assemblies

A cryptographic protocol used for secure communication ove the Internet, the successor of SSL is called?

Transport Layer Secuirty (TLS)

Which method would you call when you use a barrier to mark that a participant reached that point?

SignalAndWait

How can you schedule work to be done by a thread from a threadpool?

1. Call the ThreadPool.QueueUserWorkItem | 2. Create a new thread and set property

You are a developer at ompany xyz. You have been asked to improve the responsiveness of your WPF application. Which solution best fits the requirement?

BackgroundWorker class

Define contravariance

Allow a method to take parameters that are from a superclass of the type expected by the delegate

Define covariance

Allows a method to return a value from a subclass of the result expected by a delegate

What methods can you use to catch integer overflow exceptions?

1. Use a checked block and a try-catch-finally block | 2. Check the advanced build setting dialogue flow box and use a try-catch-finally block

True or False | Can a try-catch-finally block next inside a try-catch-finally block?

Yes

True or False A derived class can raise a base class event by using code similar to the following: if( base.EventName != null) bse.EventName(this, args)

False A derived class cannot raise an event defined in an ancestor class.

If an object subscribes to an event once and then unsubscribes twice, does the event handler throw an exception when the event is raised.?

Suppose the card class provides a stopped event that takes as parameters sender and stopped ars objects. Suppose also that the code has already created an appropriate stopped args named args. How do you raise the event?

if( Stopped != null) | Stopped(this, args);

How do you evaluate if the variable result holds the value | float.PositiveInfinity

1. result == float.PostiveInfinity 2. float.IsInfinity(result) 3. float.IsPositiveInfinity(result)

Which of the following should you not do when building a custom exception class?

Make it implement IDisposable

How are events customized?

By adding a custom event accessor and by directly using the underlying delegate type

How are events raised?

Events are raised by the declaring class Users of events can only remove or add methods to the invocation list.

Define events

A layer of 'syntatic sugar' on top of delegates to easily implement the publish/subscribe pattern.

Define lambda expression

Anonymous methods that use the => operator and form a compact way to create inline functions.

Define delegates

A type that defines a method signature and cna contain a reference to a method. Delegates can be instantiated passed around and invoked

Define Task

A unti fo work

Define scheduler

A component of the OS that slices time between threads

Define race condition

Occurs when two or more threads access the same data for write operations

Define mutual exclusion

The problem of ensuring two threads can't be in the same critical section at the same time.

Define multithreading

An operating system or hardware platform that can have several threads operating at the same time.

Define fork-join pattern

Process of spawning another thread from the current thread to do work while current thread continues. The current thread waits for spawned thread to finish (using Join)

Define EAP

Event-Based Asynchronous Pattern Pattern requires a method to be suffixed with async and provide delegates to signal completion or failure. Not recommended for new development

Define | What four conditions lead to a deadlock

1. Mutual exclusion 2. Hold and Wait 3. No preemption 4. Circular wait

Define | Deadlock

Two or more threads that attempt to acquire a lock on a resource

Define | Atomic Operation

An operation that runs once without interruption by the scheduler

Define | APM

``` Asynchronous Pattern Model Pattern split into two parts Begin : Prepares the call and expects immediate return End : Called to return result ``` Used with existing development

Define | Asynchrony

Operations run in a non-blocking fashion

How do you execute a method as a task?

1. Create a new task, then call the Start method 2. Create and run task (Task.Run()) 3. Create and run task via Task.Factory.StartNew()

Which method can be used to cancel an ongoing operation that uses a cancellation token?

Call the cancel method on the CancellationTokenSource used to create the CancellationToken

You are processing some data over the network. You use a HasNext and Read method to retrieve the data. You need to run some code on each item. What do you use?

do-while loop

You have a lot of checks in your applicaiton for null values. If a value is not null, you want to call a method on it. Which technique would you use?

null-coalescing operator

You need to iterate over a collection in which you know the number of items. You need to remove certain items from the collection. Which statement do you use?

for Cannot remove certain items from the collection using foreach

You want your type to be able to be converted from string. Which interface should you implement?

IFormattable

You want to deploy only the date portion of a DateTime according to the French culture. What method should you use?

dt.ToString("d", new CultureInfo("fr-FR")); d = specifies date fr-FR specifies French language

You are parsing a lage piece of text to replace values based on some complex algorithm. Which class should you use?

StringBuilder

Name six methods for dealing with strings

``` IndexOf LastIndexOf StartsWith EndsWith SubString ```

What is the purpose of StringBuilder?

To enhance the performance of string manipulations

Define strings

An immutable reference type

Your application is using a lot of memory. Which solution should you address with?

Use a caching element to decide which objects can be freed. You then decie the criteria for freeing memory.

Yes or No An object that is implementing IDisposable is passed to your class as an argument. Should you wrap the element in a using statement?

No The calling method should dispose of the object with a using statement

You are about to execute a piece of code that is performance sensitive. You are afraid that a garbage collection will occur during the execution of this code. Which method should you call before executing your code?

GC.Collect() Collect will execute a garbage collection, freeing as much memory as possible at that time. It makes further garbage collection less likely to happen.

When is a WeakReference used?

To maintain a reference to items that can be garbage collected when necessary.

How can yo make sure resources are freed when implementing IDisposable?

By implementing a using statement

What is the purpose of IDisposable?

To free unmanaged resources in a deterministic way.

What piece of code is executed by the garbage collector when disposing of an object?

Finalizer

What comprises memory in a C# program?

Stack (local variables) | Heap (global variables, method/functions)

You want to read the value of a private field on a class. Which Binding Flags do you use?

Instance because the filed is non-static NonPuiblic as the filed is declared private ex. BindingFlags.Instance | BindingFlags.NonPublic

Memory allocation is managed on the heap by what process?

Garbage Collection (GC)

You want to create a delegate that can filter a list of strings on a specific value. What type should you use?

Func, IEnumerable); ``` string = filter IEnumerable = input list IEnumerable = returned filtered list ```

You need to create an attribute that can be applied multiple times on a method or parameter. Which syntax should you use?

[AttributeUsage( AttributeTargets.Method | AttributeTargets.Parameter, AllowMultiple = true)]

Define expression trees

Expression trees describe a piece of code. Expression trees can be translated to something else (SQL) or compiled and executed.

Describe the purpose of the CodeDOM

Used to create a compilation unit at runtime The unit can be compiled or converted to a source file.

Define Reflection

The process of inspecting the metadata of a C# application

Define Attributes

A type of metadata that can be applied in code and queued at runtime

What is stored in a C# assembly?

Code and metadata

You want to inherit from an existing class and add some behavior to a method. Name the steps.

Use the virtual keyword on the base method Use the override keyword on the derived method

You want to create a type that can be easily sored. Which interface should you implement?

IComparable IComparable enables objects to be compared to each other.

Define IComparable

Interface used to sort elements

You want to create a hierarchy of types because you have some implementation code you want to store between all types. You also have some method signatures you want to store. What should you use?

An abstract class The abstract class enables you to store both implemented methods and method signatures that a derived class needs to implement.

Define IUnknown

Wrapper used to add com objects that are unable to be wrapped by the compiler

Define IDisposable

Facilitates working with external unmanaged resources

Define IEnumerable

Allows you to iterate over items in the collection

Name four primary default interfaces provided by the .NET framework

IComparable IEnumerable IDisposable IUnknown

How can you prevent a class from being inherited?

Mark the class as sealed

What is the significance of marking a class abstract?

The class cannot be instantiated and can function only as a base class.

Name the three C# data structures

Structs Enums Classes

Where are value types defined?

Within the .NET Framework

How are value types based?

On the number of bits used to store the type

How are value types passed to methods?

As a copy

Value types are an alias for what object?

System

How are value types stored?

Directly

How are object values passed in generic methods?

They are passed by reference

What does the designator indicate in a generic class?

Serve as a placeholder that will contain the object used

What is an advantage of using Generics in .NET?

Generics enable you to create classes that accept the type at creation time.

Name on advantage of using named parameters

You can pass the parameters in to the method in any order using parameter names

Boxing refers to ?

Converting a value type to a reference type

How do enforce encapsulation on the data members of your class?

Create private data members and Public properties

When you create an abstract method, how do you use that method in the derived class?

You must override the method in your derived class

What is the parameter in this method known as? ``` public void displayAbsoluteValue( int value = 1) { //Do Something } ```

Optional

What are two methods with the same name but with different parameters referred to as?

Overloaded methods

In the following enumeration, what will be the underlying value of Wed? enum Days{Mon-1, Tues, Wed, Thur, Fri, Sat, Sun}

What is the correct way to access the firstname property of a struct named Student

var firstName = Student.firstname;

True or False | Can structs contain methods?

True

Which declaration can assign default value to an int type:

int myInt = new int();

True or False double and float types can store values with decimals?

True

What is the maximum value you can store in an uint data type?

4,294, 967, 296

Define main property abstract methods

Abstract methods do not define and implementation

How are overloaded methods defined?

By signature name, types and parameters

What purpose do methods serve in classes?

Provide the functionality of the class

How many parameters may the default constructor specify?

None Default constructors have no parameters

How are constructors named?

With the same name as the class

Do constructors specify a return type?

What is the purpose of the constructor?

To initialize the class

What is the purose of fields within a class?

To house data for the class

To avoid unwanted modifications, how should fields be marked?

private

Name the modifiers that can be used when declaring classes?

``` internal private public protected protected internal ```

What is the purpose of class modifiers?

To determine access for classes and class members

What is the purpose of member functions within a class?

To describe functionality

What is the purpose of member variables within a class?

To describe characteristics or properties

Reference types are commonly referred to as?

classes

What is the underlying type of enums?

Integers beginning at 0, unless the declaration specified in declaration specifies otherwise

How are enumerations formed?

As a list of named constants

How are structs passed to methods?

By value

Define structs

Lightweight data structures

How can derived classes act on base classes marked as virtual?

Derived classes can override virtual methods to add or replace behavior.

A class is limited to inheriting how many interfaces?

No limit, unlimited

A class is limited to inheriting how many classes?

One, C# support single class inheritance

Define interface

An interface specifies the public elements a type myst implement

Define inheritance

The process in which a class is derived from another class or from an interface

Define generic types

Type parameter used to make code more flexible

Name the types in C#

Value Types | Reference Types

Define casting

An explicit conversion that requires special syntax

Name the conversion options for types

Implicit | Explicit

Define boxing

Boxing occurs when a value type is treated as a reference type

What keyword can be used to ease the static typing of C# and improve interoperability with other languages

dynamic

You have a class that implements two interfaces with the same name. Interface IA should be the default implementation. Interface IB should be used only in special situations. How do your implement these interfaces?

Implement IA implicitly (makes IA default) and IB explicitly.

You need to expose some data from a class. The data can be read by other types but can be changed only by derived types. What should you use?

A public property with a protected set modifier.

What access modifiers should you use to make sure that a method in a class can only be accessed inside the same assembly by derived types?

The class should be marked internal (only accessed inside project) The members marked as protected (accessed by derived types)

Name two uses of explicit interface implementation

1. To hide information | 2. Implement interfaces with duplicate signatures

Name the five access modifiers in C# development

``` private public internal protected protected internal ```

How is accessability to types and type elements restricted?

Through use of access modifiers

Define getters and setters

Property accessors that can run additional code

How is data encapsulated in object-oriented design?

Through use of properties

Why is encapsulation important in object-oriented design?

Hides internal details and improves usability of type

You pass a struct variable into a method as and argument. The method changes the variable; however, when the method returns the method has not changed. What happened?

Passing a value type makes a copy of the data. The original value has not changed.

You are creating a generic class that should work only with reference types. Which type constraint should you add?

where T:struct

You are creating a new collection type and you want to make sure the elements in it can be easily accessed. What should you add to the type?

Indexer Property

Define overriding

Enables you to redefine functionality from a base class in a derived class.

How are C# types created?

``` Using ; Constructors Methods Properties Fields Indexers ```

Which method will you use to Signal and EventWaitHandle?

set

In a multithreaded application how would you increment a variable called counter in a lock free manner?

Interlocked.Increment(ref counter); Interlocked.Add(ref counter, 1);

What code is equivalent with ``` lock(syncObject) { // Do something } ```

Monitor.Enter(syncObject); ``` try { } finally { Monitor.Exit(syncObject) } ```

Name methods that can be used to start or continue tasks

ContinueWith WhenAll WhenAny

Name two methods to create and start a task

1. Task.Run() | 2. Task.Factory.StartNew()

An asynchronous unit of work is known as a ?

Task

What instrument is used to reduce resource consumption when using threads?

Threadpools

Which class abstracts task creation and makes it easier to deal with loops and parallel invokation of methods?

Parallel

What class is used to run code in parallel?

The Parallel class

What extension is used to run queries in parallel?

PLINQ

You are creating a complex query that does not require any particular order and you want to run in parallel. Which method should you use?

AsParallel()

You have a lot of items that need to be processed. For each item you need to perform a complex calculation. Which technique should you use?

Parallel.For Best for executing large number of items and processing concurrently.

What class is used to create threads explicitly?

Thread class

What class is used to allow runtime to handle threads?

Threadpools

What is the recommended method to handle multithreaded code?

The Task object

You are working on an ASP.NET application that retrieves some data from another web server and then writes the response to the database. Should you use async and await?

Yes This will free server resources to serve other requests waiting for I/O to complete

What operators are sued to write asynchronous code more easily?

async and await

What is the advantage of a thread?

Improves responsiveness and enables multiple CPU processing.

How do u describe a thread?

A virtualized CPU

What collection is used to work with data in a multithreaded environment?

Concurrent

Define anonymous method

A method without a name. You create a delegate that refers to code the method should contain

How are delegates defined?

``` delegate(params) { // Do Something } ``` Ex. Func Square = delegate(float x) { return x * x; };

What is the general form of a lambda expression?

() => statement

What is the general form of an asynchronous lambda?

``` async (params) => { // Do Something }; ```

What is the general form of a statement lambda?

``` () => { // Do Something; return value; }; ```

Define subscriber

The class that catches the event

Define publisher

An object that raises the event

What operators are used to subscribe/unsubscribe to an event?

``` += Subscribes -= Unsubscribe ```

Define syntax for declaring an event

AccessModifier event delegate eventName Ex. public delegate void customEventHandler(); public event customEventHandler eventName;

Describe the arguments passed to events

First parameter is the object raising the event Second parameter is an object derived from EventArgs

Define eventArgs

Arguments relevant to the event

Describe form for declaring event arguments

``` class customEventArgs:EventArgs { // instance variables public customEventArgs(instance variables) { // Do someting } } ```

Define Microsoft's generic EventHandler delegate

public event EventHandler customEventName

Define event inheritance

``` Problem Events can only be raised from within the class that declared it. ``` ``` Solution Provide the base class a protected method that raises the event, then a derived class can call the method ```

Define structure of inherited event

``` protected virtual void onMethod(customEventArg) { // Do something } ```

Define the statement that subscribes the myButton_Click event handler to catch the myButton controls click event.

myButton.Click += myButton_Click;

Suppose the Employee class is derived from the Person class and the Person class defines an AddressChanged event. Which of the following should you do to allow an Employee object to raise this event?

1. Create an OnAddress changed method in the Person class that raises the event. 2. Make the Employee class call OnAddressChanged as needed. 3. Make the code in the Person class that used to raise the event call the OnAddressChanged method instead.

Suppose the MovedEventHandler is defined by the statement delegate void MovedEventHandler(); How do you define the Moved event?

public event MovedEventHandler Moved; or public event Action Moved;

Define the attributes of statement lambda's

A statement lambda can include more than one statement A statement lambda must use braces If a statement lambda returns a value it must use a return statement

In the variable declaration Action processor the variable processor represents?

Methods that take Order as object and return void

If an employee class inherits from the Person class, covariance allows you to?

Store a method that returns employee in a delegate that returns a Person

If the Employee class inherits from the Person class. Contravariance allows you to?

Store a method that takes Person as a parameter in a delegate that represents methods that take an Employee as parameter

Describe delegate variables

1. A struct or class can contain fields that are delegate variables 2. You can make an array or list of delegate variables 3. You can use addition to combine delegate variables and subtraction to remove a method from a series

How is a delegate defined?

accessModifier delegate returnType delegateName(params)

Name the tools associated with multithreading

TPL (Task Parallel Library) Parallel class PLINQ async and await

What actions can be performed with exceptions?

throw catch finally

Define events

Events help to create the | publish-subscribe architecture

Define lambda expression

Shorthand syntax for creating inline anonymous methods

Define delegates

Objects that point to a method and can be used to make methods

Name the jump statements

``` break continue goto return throw ```

Name the iteration statements

for foreach while do-while

Name the decision statements

if switch ? (conditional operator) ?? (null coalescing operator)

In a multithreaded environment, it is important to manage synchronization of shared data using which tool?

lock statment

You are creating a custom exception called LogonFailedException. Which constructors should you add at minimum?

LogonFailedException(); //default LogonFailedException(string); LogonFailedException(string, exception);

What keyword is used to raise an exception?

By using the throw keyword

How can you specify code to run whether or not an exception occurs?

with the finally block

How are exceptions typically caught in the .NET framework?

using the try..catch block

Suppose the variable Note is declared by the statement Action Note. Correctly initialize Note to an expression lambda.

Note = () => MessageBox.Show("Hi");

Suppose the variable result is declared by the statement Func result; Correctly initialize result to expression lambda.

result = (float x) => x * x; or result = (x) => x * x;

Suppose F is declared by the statement Func F Correctly initialize F to an anonymous method

F = delegate(float x) { return x* x; }

In the variable declaration Func processor; The variable processor represents?

A method that takes no parameters and returns and Order object

The process of converting a boxed value back to it's original value is known as ?

unboxing

How are values displayed at a very high level?

Through standard formatting strings

Define narrowing conversion

A data type conversion where the destination type cannot hold all possible values of the source. Requires an explicit conversion

What is interoperability

Interoperability enables managed code to use classes provided by unmanaged code not under control of CLR

Define the intern pool

A table maintained by the CLR that contains a reference to every unique string used by the program

What type of conversion occurs when a program automatically converts a value from one datatype to another

implicit

Define immutable

A data type is immutable if its value cannot be changed after creation

What do you create to build formats that are not provided by standard formatting strings?

custom formatting strings

Describe an explicit conversion

Using a cast or method to explicitly tell a program how to convert a value from one type to another

What format item used by string.Format indicates how an argument should be formatted?

The composit format { index[length][:formatString] }

What is the CLR?

Common Language Runtime Manages execution of C# and other .NET programs

What is the process of converting a value type such as a bool or integer into an object or interface?

boxing

Name the most common DateTime formats

``` d: short date D: long data f: full date, short time F:full date, full -time M/m : Month, day t: short time T: long time Y/y: year, month g: general, short time G: general, full time ```

Why are standard format strings the preferred method?

They are locale-aware

Name two methods that convert values into strings

.ToString() string.Format()

What classes provide methods for writing and reading characters and lines with an underlying StringBuilder object?

StringWriter and StringBuilder

Your code catches an IOExceptionwhen a file cannot be accessed. You want to give more information to the caller of your code. What do you do?

Throw a new exception with extra information that has the IOException as InnerException

You are checking the arguments of your method fro illegal null values. If you encounter a NULL value, which exception do you throw>

ArgumentNullException

Define exceptions

Objects that contain data about the exceptions

How are errors reported in the .NET framework

via exceptions

You have a private method in your class and you want to make invocation of the method possible by certain callers. What do you do?

Use a method that returns a delegate to authorized callers

You have declared an event on your class, and you want outside users of your class to raise this event. What do you do?

Add a public method to your class that raises the event

You are using a multicast delegate with multiple subscribers. You want to make sure that all subscribers are notified, even if an exception is thrown. What do you do?

Manually raise the event by using GetInvocationList

Define Sentinal

A value used to signal the end for execution in a loop

Define IEnumerable

A code component in C# that supports iterations

Name three generic delegate types defined by the .NET framework

Action Func Predicate

Define contravariance

Returns a value from a superclass of the type expected by the delegate

Define covariance

Returns a value from a subclass of the result expected by a delegate

Name the steps to implementing a delegate

1. Use the delegate keyword to define delegate type 2. Create variables of delegate type 3. Set variables equal to methods that match delegates and return type 4. Invoke the variable

How to declare a delegate

accessModifier delegate returnType DelegateName(); ex private delegate int FunctionDelegate(float x);

What are best practices for naming delegate types

delegate types should end with the suffix Delegate ex. FunctionDelegate If a delegate is used as a collback, when code finishes suffix with Callback ex FunctionCallback

Define Action delegates

A method that returns void and accepts between 0 and 18 parameters

Define Func delegates

A method that returns a value and accepts between 0 and 18 parameters

Provide example of replacing custom delegate with action delegate

private delegate void FunctionDelegate(param) private FunctionDelegate FunctionParamMethod; replace with: private Action FunctionParamMethod;

Provide example of replacing custom delegate with Func delegate

private delegate datatype FunctionDelegate(param) private FunctionDelegate FunctionParamMethod; replace with: private Func FunctionParamMethod;

In the following code sample, will the second if structure be evaluated? ``` bool condition = true; if(condition) if( 5 < 10) { Console.WriteLine("5 is less than 10"); } ```

Yes

What kind of result is returned in the condition part of an if statement?

bool

You need to move a logical comparison where two values must return true in order for your code to execute the correct statement. What do you do?

You want to declare an integer variable called myVar and assign it to the value 0. How can you accomplish this?

int myVar = 0;

If you want to iterate over the values in an array of integers called arrNumbers to perform an action on them, which loop statement enables you to do this?

``` foreach(int numer in arrNumbers) { // Do Something } ```

What is the purpose of the break in a switch statement?

It causes the code to exit the switch statement

What are the four main repetition structures in C#?

for foreach while do-while

How many times will this loop execute? ``` int value = 0; do { Console.WriteLine(value); }while(value > 10); ```

Once

A data type conversion where the destination type can hold all values in the source type is known as ?

Widening conversion

What encoding is used by the .NET framework

UTF-16, 16 bits per character

Define unicode

A standard for encoding characters used by scripts in various locales around the world

What pool holds an instance of every unique string?

The intern pool

String values do not change, they are referred to as ?

immutable

What is a dynamic type

A static type that is not evaluated until runtime

When does unboxing occur?

When converting a reference type to a value type

How does boxing occur?

When converting a value type to a reference type

What class is used to convert data to and from an array of bytes?

System.BitConverter

Name the methods in System.Convert

ToBoolean, ToDouble, ToSingle, ToByte, toInt16, ToString, ToChar, ToInt32, ToInt16, ToDateTime, ToInt64, TUInt32, ToDecimal, ToSByte, ToUInt64

What class provides methods that convert from one type to another?

System.Convert

Name some common styles from System.Globalization.NumberStyles

``` Integer HexNumber Number Float Currency Any ```

What enumeration allows Parse and TryParse to understand special symbols?

System.Globalization.NumberStyles

What method can be used to parse text and see if ther is an error?

TryParse()

How is text parsed into values?

using the Parse() method

What is the purpose of the as operator?

To convert an object into a compatible type or NULL if compatibility doesn't exist.

What is the purpose of the is operator?

To determine if a variable is compatible with a specific type

How are floating point operations checked for overflow or underflow?

By checking the Infinity and/or NegativeInfinity properties

How are integer overflows captured?

Using the checked block or Advanced Builds Setting Dialog

Yes or No Do explicit conversions require a cast operator?

Yes

Yes or No Do implicit conversions require a cast operator?

Which technique should you use to watch for floating point operations that cause overflow or underflow conditions?

Check the result for the Infinity or NegativeInfinity

Which statement can be used to capture integer overflow or underflow errors?

checked

Can the string class space method be used to create a string containing 10 spaces?

Name three common string methods

IndexOf StartsWith Trim (ther are others)

If Employee inherits from Person and Manager inherits from Employee then assign a Person to an Employee type.

Person alex = new Employee();

The statement object obj=72 is an example of?

boxing

What is the best way to store an integer value typed by the user in a variable?

TryParse

If i is an int and l is a long then i = (int) l is what ype of conversion?

narrowing conversion

Generate a string containing the text "Vend, Vidi, Vici"

String.Format("{0}, {1},{2}", "Vend", "Vidi", "Vici");

Assuming total is a decimal variable holding the value 1234.56, which of he following statements display total with currency format $1,234.56?

Console.WriteLine( total.ToString("c"));

Name the characteristics of narrowing conversions

The source and destination must be compatible

Name the characteristics of widening conversions

Any value of the source type can fit into the destination type The conversion will not result in loss of magnitude but may result in loss of precision An explicit cast is optional

Why are properties valuable?

To perform data validations on incoming and outgoing data values

What operations can be performed on properties?

read/write read only write only

What is the purpose of properties?

To present the public interface to your class

In encapsulation, how is data exposed?

Through properties

In encapsulation what access modifier is specified for member variables?

private

What is the purpose of encapsulation?

Functionality and data are enclosed as part of the class

What is another name for data hiding?

encapsulation

What enables you to pass arguments to a method in order other than specified in the message signature?

named parameters

What allows for giving parameters in a method a name?

named parameters

What are the requirements when using optional parameters?

Must exist after required parameters If multiple optional parameters exist and a value is specified for one, all preceding optional parameters must also be supplied values

When is a default value used?

If none is passed by caller

How are optional parameters defined?

By including a default value

Name the type of parameters that enable you to choose the parameters required in a method

optional parameters

What type of classes are overridden?

Virtual and abstract methods in base classes

What type of method provides the means to change method behavior in a derived class?

overriden methods

What is the purpose of extension methods?

To extend existing lasses by adding methods without recompiling

Where are extension methods applied?

To your own types or existing types in .NET

What is the purpose of overridden methods?

To hide the implementation of a method of the same name in the base class

Where are abstract methods defined?

Abstract methods can only be defined in abstract classes

You are creating a custom Distance class. You want to ease the conversion from your Distance class to a double. What should you add?

An implicit cast operator

What area is used by the .NET compiler to store reference type variables?

heap

Variables that store the characteristics data for a class are referred to as?

fields

The object that listens for an event to be raised is?

The event subscriber

The object that raises the event for the listener or subscriber is the ?

event publisher

A distinct type consisting of a set of named constants is known as an ?

enumeration

The hiding of details around the implementation of an object so there are no external dependencies on the particular implementation?

encapsulation

Components in code that are used to store data within a program are referred to as?

data structures

What class methods are executed when an object of a given type is created?

constructors

What are coding components that enable you to create custom types to group together characteristics, mehtods and events

classes

What is used to encapsulate data and functionality into one unit of code

class files

What methods are used to access hidden number variables?

accessor methods

When can an abstract modifier be used?

With classes, methods, properties, indexers and events

When is an abstract modifier used?

To indicate that a class is intended to be only a base class of other classes

What technique is used to define methods without specifying the types for parameters at definition stage?

generic types

What is the purpose of the generic type?

Enables type-safe coding Increase performance due to reduction in conversions, boxing/unboxing.

What types are used as a placeholder at define stage that is replaced by type during instantiation?

generic types

How are indexed properties accessed?

Using an index in the same manner as arrays

What properties allow array like access to group of items?

idexers (indexed properties)

What are instance fields?

fields related to a specific instance. Values are not shared among objects of the same class.

You are using an ArrayList as a collection for a list of points, which are a custom struct. You are experiencing performance problems when working with a large amount of points. What do yo have to do?

Use a generic collection instead of ArrayList

Define properties

Members that provide a flexible mechanixm to read, write or compute the values of private fields.

When is the override access method used?

To extend or modify the abstract or virtual implementation of an inherited method, property, indexer or event.

What is the purpose of the modifier?

Modify declarations of types and type members

What is used to provide functionality for a class?

method

What is a memory address?

An addressable location in computer memory used to store and retrieve values

You want to determine whether the value of an object reference is derived from a particular type. Which C# feature can you use?

An as operator An is operator

To parse a string that might contain a currency value such as $1,234.56 you should pass the Parse or TryParse method which of the following values?

NumberStyles.Currency

An area of memory used by the .NET compiler to store value types during program execution is known as the?

Stack

Methods with identical names for procedures that operate on different data types are referred to as ?

overloaded methods

The unique identifying components of a method, such as return type, name and parameter is known as it's?

signature

class files or other objects represented as references to the actual data (memory address) are referred to as ?

reference types

In entity framework, which class is responsible for maintaining the bridge between a database engine and C# code?

DbContext

Which method is used to return a specific number of objects from a quuery result?

Take()

Which of collection types is used to retrieve data in a Last-In, Last-Out (LIFO) way?

Stack

What keyworkd is used to filter a query?

Where()

Which extension method is used to join two queries?

join()

Suppose you're writing a method that retrieves the data from an MS Access 2013 database. The method must meet the following requirements; 1. Be read-only 2. Be able to use the data before the entire data set is retrieved 3. Minimize the amount of system overhead and amount of memory usage What type of object should be used in the method?

Because MS Access OleDbDataReader

Suppose you have the following code segment: 01. ArrayList arrays = new ArrayList(); 02. int i = 10 ; 03. int j; 04. arrays.Add(i); 05. j = arrays[0]; You need to resolve the error that occurs at line 05 ("Cannot implicitly convert type object to int"). You need to ensure that the error gets removed. Which code should you replace in line 05?

j = (int)arrays[0];

``` Suppose you have the following code snippet: 01. class Person 02. { 03. public int ID { get; set; } 04. public string Name { get; set; } 05. public int Age { get; set; } 06. } 07. Dictionary people = new Dictionary 08. { 09. {21, new Person {ID = 1, Name="Ali", Age = 22 } }, 10. {22, new Person {ID = 2, Name="Sundus", Age = 21 } }, 11. {23, new Person {ID = 3, Name="Asad", Age = 22 } }, 12. {24, new Person {ID = 5, Name="Naveed", Age = 21 } }, 13. }; 14. 15. people.Add(24, new Person { ID = 6, Name = "Malik", Age = 10 }); ``` The application fails at line 15 with the following error message: "An item with the same key has already been added." You need to resolve the error. Which code segment should you insert at line 14? A) if(!people.ContainsKey(24)) B) foreach (Person person in people.Values.Where(t=>t.ID !=24)) C) foreach (KeyValuePair key in people.Where(t=>t.Key != 24)) D) foreach (int key in people.Keys.Where(k=>k!=24))

A) if(!people.ContainsKey(24))

``` You’re creating an application that counts the number of times a specific word appears in a text file. See the following code snippet: 01. class Demo 02. { 03. ConcurrentDictionary words = 04. new ConcurrentDictionary(); 05. public Action ProcessDir() 06. { 07. Action act = (dirInfo => 08. { 09. var files = dirInfo.GetFiles("*.cs").AsParallel(); 10. files.ForAll( 11. fileinfo => 12. { 13. var content = File.ReadAllText(fileinfo.FullName); 14. var sb = new StringBuilder(); 15. foreach (var item in content) 16. { 17. sb.Append(char.IsLetter(item) ? 18. item.ToString().ToLowerInvariant() : " "); 19. } 20. var wordlist= sb.ToString().Split(new[] { ' ' }, 21. StringSplitOptions.RemoveEmptyEntries); 22. foreach (var word in wordlist) 23. { 24. 25. } 26. }); 27. var dir = dirInfo.GetDirectories() 28. .AsParallel(); 29. dir.ForAll(ProcessDir()); 30. }); 31. return act; 32. } 33. } ``` You need to populate a words object with the list of words and the number of occurrences of each word, and also ensure that the updates to the ConcurrentDictionary object can happen in parallel. Which code segment should you insert at line 24? ``` A) words.AddOrUpdate(word, 1, (s, n) => n + 1); B) int value; if(words.TryGetValue(word, out value)) { words[word] = value++; } else { words[word] = 1; } ```

A) words.AddOrUpdate(word, 1, (s, n) => n + 1);

You have a List object that is generated by executing the following code: List subjects = new List() { "English","Computer","Maths","Physics" }; You have a method that contains the following code: 01. bool GetSameSubjs(List subj, string searchSubj) 02. { 03. var findSubj = subj.Exists((delegate (string subjName) 04. { 05. return subjName.Equals(searchSubj); 06. } 07. )); 08. return findSubj; 09. } You need to alter the method to use a lambda statement. How should you rewrite lines 03 through 06 of the method? A) var findSubj = subj.First(x => x == searchSubj); B) var findSubj = subj.Where(x => x == searchSubj); C) var findSubj = subj.Exists(x => x.Equals(searchSubj)); D) var findSubj = subj.Where(x => x.Equals(searchSubj));

C) var findSubj = subj.Exists(x => x.Equals(searchSubj));

``` Which of the following two interfaces should you use to iterate over a collection and release the unmanaged resources. A) IEquatable B) IEnumerable C) IDisposable D) IComparable ```

B) IEnumerable | C) IDisposable

You are creating an application that will parse a large amount of text. You need to parse the text into separate lines and minimize memory use while processing data. Which object type should you use? A) DataContractSerializer B) StringBuilder C) StringReader D) JsonSerializer

B) StringBuilder

You need to store the values in a collection. The values must be stored in the order that they were added to the collection. The values must be accessed in a first-in, first-out order. ``` Which type of collection should you use? A) SortedList B) Queue C) ArrayList D) Hashtable ```

B) Queue

You need to choose a collection type which internally stores a key and a value for each collection item, provides objects to iterators in ascending order based on the key, and ensures that items are accessible by a zero-based index or by key. Which collection type should you use? A) SortedList B) Queue C) Array D) HashTable

A) SortedList

You are creating an application that uses a class named Person. The class is decorated with the DataContractAttribute attribute. The application includes the following code snippet: 01. MemoryStream WritePerson(Person person) 02. { 03. var ms = new MemoryStream(); 04. var binary = XmlDictionaryWriter.CreateBinary(ms); 05. var ser = new DataContractSerializer(typeof(Person)); 06. ser.WriteObject(binary, person); 07. 08. return ms; 09. } You need to ensure that the entire Person object is serialized to the memory stream object. Which code segment should you insert at line 07? A) binary.WriteEndDocument(); B) binary.WriteEndDocumentAsync(); C) binary.WriteEndElementAsync(); D) binary.Flush();

A) binary.WriteEndDocument();

``` You are developing a class named Person. See the following code snippet: 01. class People 02. { 03. Dictionary people = new Dictionary(); 04. public void Add(string name, int age) 05. { 06. people.Add(name, age); 07. } 08. 09. } It has the following unit test: public void UnitTest1() { People people = new People(); people.Add("Ali", 22); people.Add("Sundus", 21); int expectedAge = 21; int actualAge = people["Sundus"]; Assert.AreEqual(expectedAge, actualAge); } You need to ensure the unit test will pass. What code snippet you should insert at line 08? A) public Dictionary People { get { return people; } } B) public int this[string name] { get { return people[name]; } } C) public Dictionary People = new Dictionary(); D) public int salary(string name) { return people[name]; } ```

``` B) public int this[string name] { get { return people[name]; } } ```

You’re creating an application that converts data into multiple output formats; it includes the following code snippets. 01. class TabDelimitedFormatter : IFormatter 02. { 03. readonly Func suffix = 04. col => col % 2 == 0 ? '\n' : '\t'; 05. public string Output(IEnumerator iterator, int size) 06. { 07. 08. } 09. } 10. interface IFormatter 11. { 12. string Output(IEnumerator iterator, int size); 13. } You need to minimize the completion time of the GetOutput() method. Which code segment should you insert at line 07? A) string output = null; for(int i = 1; iterator.MoveNext(); i++) { output = string.Concat(output, iterator.Current, suffix(i)); } B) var output = new StringBuilder(); for(int i = 1; iterator.MoveNext(); i++) { output.Append(iterator.Current); output.Append(suffix(i)); } C) string output = null; for(int i = 1; iterator.MoveNext(); i++) { output = output + iterator.Current + suffix(i); } D) string output = null; for(int i = 1; iterator.MoveNext(); i++) { output += iterator.Current + suffix(i); }

``` B) var output = new StringBuilder(); for(int i = 1; iterator.MoveNext(); i++) { output.Append(iterator.Current); output.Append(suffix(i)); } ```

Suppose you’re writing a method named ReadFile that reads data from a file. You must ensure that the ReadFile method meets the following requirements: 1. It must not make changes to the data file. 2. It must allow other processes to access the data file. It must not throw an exception if the application attempts to open a data file that does not exist. Which code segment should you use? A) var fs = File.Open(Filename, FileMode.OpenOrCreate, FileAccess.Read, FileShare.ReadWrite); B) var fs = File.Open(Filename, FileMode.Open, FileAccess.Read, FileShare. ReadWrite); C) var fs = File.Open(Filename, FileMode.OpenOrCreate, FileAccess.Read, FileShare.Write); D) var fs = File.ReadAllLines(Filename); E) var fs = File.ReadAllBytes(Filename);

``` A) var fs = File.Open(Filename, FileMode.OpenOrCreate, FileAccess.Read, FileShare.ReadWrite); ```

You’re using ADO.NET Entity Framework to retrieve data from a database in MS SQL Server. Suppose you have the following code snippet: 01. public DataTime? OrderDate; 02. IQueryable GetOrderByYear(int year) 03. { 04. using (var context = new NortwindEntities()) 05. { 06. var orders = from order in context.Orders; 07. 08. select order; 09. return orders.ToList().AsQueryable(); 10. } 11. } You need to ensure the following requirements: 1. Return only orders that have an OrderDate value other than null. 2. Return only orders that were placed in the year specified in the OrderDate property or in a later year. Which code segment should you insert at line 07? A) Where order.OrderDate.Value != null && order.OrderDate.Value.Year > = year B) Where order.OrderDate.Value = = null && order.OrderDate.Value.Year = = year C) Where order.OrderDate.HasValue && order.OrderDate.Value.Year = = year D) Where order.OrderDate.Value.Year = = year

A) Where order.OrderDate.Value != null && order.OrderDate.Value.Year > = year

An application has the following code: 01. class Person 02. { 03. public string Name { get; set; } 04. public int Age { get; set; } 05. } 06. static IEnumerable GetPersons(string sqlConnectionString) 07. { 08. var people = new List(); 09. SqlConnection sqlConnection = new SqlConnection(sqlConnectionString); 10. using (sqlConnection) 11. { 12. SqlCommand sqlCommand = new SqlCommand("Select Name, Age From 13. Persons", sqlConnection); 14. 15. using (SqlDataReader sqlDataReader = sqlCommand.ExecuteReader()) 16. { 17. 18. { 19. Person person = new Person(); 20. person.Name = (string)sqlDataReader["Name"]; 21. person.Age = (int)sqlDataReader["Age"]; 22. 23. people.Add(person); 24. } 25. } 26. } 27. return people; 28. } The GetPersons() method must meet the following requirements: 1. Connect to a Microsoft SQL Server database. 2. Create Animal objects and populate them with data from the database. Which two actions should you perform? A) Insert the following code segment at line 17: while(sqlDataReader.NextResult()) B) Insert the following code segment at line 14: sqlConnection.Open(); C) Insert the following code segment at line 14: sqlConnection.BeginTransaction(); D) Insert the following code segment at line 17: while(sqlDataReader.Read()) E) Insert the following code segment at line 17: while(sqlDataReader.GetValues())

B) Insert the following code segment at line 14: sqlConnection.Open(); C) Insert the following code segment at line 14: sqlConnection.BeginTransaction();

Suppose you have a collection of integer values. You define an integer variable named IntegerToRemove and assign a value to it. You declare an array named filteredIntegers. You must to do the following things. Remove duplicate integers from the integer array. Sort the array in order from the highest value to the lowest value. Remove the integer value stored in the integerToRemove variable from the integers array. Which LINQ query would you need to create to meet the requirements? A) int[] filteredIntegers = integers.Where(value => value != integerToRemove).OrderBy(x => x).ToArray(); B) int[] filteredIntegers = integers.Where(value => value != integerToRemove).OrderByDescending(x => x).ToArray(); C) int[] filteredIntegers = integers.Distinct().Where(value => value != integerToRemove).OrderByDescending(x => x).ToArray(); D) int[] filteredIntegers = integers.Distinct() .OrderByDescending(x => x).ToArray();

C) int[] filteredIntegers = integers.Distinct().Where(value => value != integerToRemove).OrderByDescending(x => x).ToArray();

Suppose you’re creating an application that includes the following code, which retrieves JSON data. You need to ensure that the code validates the JSON. 01. bool ValidateJSON(string json, Dictionary result) 02. { 03. 04. try 05. { 06. result = serializer.Deserializer>(json); 07. return true; 08. } 09. catch 10. { 11. return false; 12. } 13. } ``` Which code should you insert at line 03? A) var serializer = new DataContractSerializer(); B) DataContractSerializer serializer = new DataContractSerializer(); C) var serializer = new XmlSerializer(); D) var serializer = new JavaScriptSerializer(); ```

D) var serializer = new JavaScriptSerializer();

``` Suppose you have a List people = new List(); You need to create an extension method that will return the correct number of Person objects from the people list that can be displayed on each page and each page has a uniform page size. Which code snippet should you use? A) Public static IEnumerable Page(IEnumerable source, int page, int pagesize) { return source.Take((pagesize - 1) * page).Skip(pagesize); } B) Public static IEnumerable Page(this IEnumerable source, int page, int pagesize) { return source.Skip((page - 1) * pagesize).Take(pagesize); } C) static IEnumerable Page(IEnumerable source, int page, int pagesize) { return source.Skip((pagesize - 1) * page).Take(pagesize); } D) Public static IEnumerable Page(this IEnumerable source, int page, int pagesize) { return source.Take((page - 1) * pagesize).Skip(pagesize); } ```

B) Public static IEnumerable Page(this IEnumerable source, int page, int pagesize) { return source.Skip((page - 1) * pagesize).Take(pagesize); }

``` Suppose you’re developing an application that needs to read the data from a file and then release the file resources. Which code snippet should you use? A) string data; using (StreamReader readfile = new StreamReader("data.txt")) { while ((data = readfile.ReadLine()) != null) { Console.WriteLine(data); } } B) string data; StreamReader readfile = null; using ( readfile = new StreamReader("data.txt")) { while ((data = readfile.ReadLine()) != null) { Console.WriteLine(data); } } C) string data; StreamReader readfile = new StreamReader("data.txt"); while ((data = readfile.ReadLine()) != null) { Console.WriteLine(data); } D) string data; StreamReader readfile = null; try { readfile = new StreamReader("data.txt"); while ((data = readfile.ReadLine()) != null) { Console.WriteLine(data); } readfile.Close(); readfile.Dispose(); } finally { } ```

``` A) string data; using (StreamReader readfile = new StreamReader("data.txt")) { while ((data = readfile.ReadLine()) != null) { Console.WriteLine(data); } } ```

``` Suppose you are developing an application that includes the following code: List list = new List { 80, 75, 60, 55, 75 }; You have to retrieve all the numbers that are greater than 60 from a list. Which code should you use? A) var result = from i in list where i > 60 select i; B) var result = list.Take(60); C) var result = list.First(i => i > 80); D) var result = list.Any(i => i > 80); ```

A) var result = from i in list where i > 60 select i;

``` You want to configure your application to output more trace data. What would you use for the configuration setting? A) Listener B) Filter C) Switch D) Trace ```

C) Switch

You are developing an assembly that will be used by server applications. You want to make the update process of this assembly as smooth as possible. What steps would you take? A) Create WinMD Assembly B) Deploy Assembly to GAC C) Sign the assembly with the storing name D) Delay sign the assembly

B) Deploy Assembly to GAC

``` You need to send your data to a receiver and want no one to tamper with your data. What would you use? A) X509Certificate2.SignHash B) RSACryptoServiceProvider.Enrypt C) UnicodeEncoding.GetBytes D) Marshal.ZeroFreeBSTR ```

A) X509Certificate2.SignHash | C) UnicodeEncoding.GetBytes

``` You need to validate an XML file. What would you use? A) XSD B) RegEx C) StringBuilder D) JavaScriptSerializer ```

A) XSD

``` Which method is easiest to find the problem if you have no idea what it is? A) Using Profiler B) Profiling by Hand C) Using Performance Counter D) Debugging ```

A) Using Profiler

``` To build a project you need a PDB file of: A) Previous build version B) Any build version C) Current Solution File D) Same build version ```

D) Same build version

``` Which class should preferably be used for tracing in Release Mode? A) Debug B) Trace C) TraceSource D) All of the above ```

C) TraceSource

Which bindingflags are useful for getting the private data instance? A) BindingFlags.NonPublic | BindingFlags.Instance B) BindingFlags.Private | BindingFlags.Instance C) BindingFlags.NonPrivate | BindingFlags.NonStatic D) BindingFlags.Private | BindingFlags.NonStatic

A) BindingFlags.NonPublic | BindingFlags.Instance

``` Which of the following methods is used for getting the information of a current assembly? A) Assembly. GetExecutingAssembly(); B) Assembly.GetExecutedAssembly(); C) Assembly.GetCurrentAssembly(); D) Assembly.ExecutingAssembly(); ```

A) Assembly. GetExecutingAssembly();

``` Which of the following commands is required to create a strong name key? A) sn -k {assembly_name}.snk B) sn k {assembly_name}.snk C) gacutil -i {assembly_name}.snk D) gacutil i {assembly_name}.snk ```

A) sn -k {assembly_name}.snk

Salt Hashing is done by: A) Merging data with a random value and performing Cryptography B) Merging data with a random value and performing Cryptanalysis C) Merging data with a random value and performing Encryption D) Merging data with a random value and performing Hashing

D) Merging data with a random value and performing Hashing

You are developing an application which transmits a large amount of data. You need to ensure the data integrity. Which algorithm should you use? A) RSA B) HMACSHA256 C) Aes D) RNGCryptoServiceProvider

B) HMACSHA256

``` The application needs to encrypt highly sensitive data. Which algorithm should you use? A) DES B) Aes C) TripleDES D) RC2 ```

B) Aes

``` How would you throw an exception to preserve stack-trace information? A) throw; B) throw new Exception(); C) throw e; D) return new Exception(); ```

A) throw;

``` You need to validate a string which has numbers in 333-456 format. Which pattern should you choose? A) @"\d\d-\d\d" B) @"\n{3}-\n{3}" C) @"[0-9]+-[0-9]" D) @"\d{3}-\d{3}" ```

D) @"\d{3}-\d{3}"

You are required to install an assembly in GAC. Which action should you take? A) Use the Assembly Registration tool (regasm.exe) B) Use the strong name tool (sn.exe) C) User Microsoft register server (regsvr32.exe) D) Use the Global Assembly Cache tool (gacutil.exe) E) Use Windows installer 2.0

D) Use the Global Assembly Cache tool (gacutil.exe) | E) Use Windows installer 2.0

You have the following code snippet: If(! PerformanceCounterCategory.Exists(“CounterExample”)) { Var counters=new CounterCreationDataCollection(); Var counter1=new CounterCreationData { CounterName=”Counter1”, CounterType=PerformanceCounterType.SampleFraction }; Var counter2=new CounterCreationData { CounterName=”Counter2” }; Counters.Add(counter1); Counters.Add(counter2); PerformanceCounterCategory.Create(“CounterExample”,””,PerformanceCounterCategoryType. MultiInstance,counters); } You need to ensure that counter1 is available for performance monitor. Which code segment should you use? A) CounterType=PerformanceCounterType.RawBase B) CounterType=PerformanceCounterType.AverageBase C) CounterType=PerformanceCounterType.SampleBase D) CounterType=PerformanceCounterType.CounterMultiBase

C) CounterType=PerformanceCounterType.SampleBase

``` You have to class ExceptionLogger and its method LogExecption, which logs the exception. You need to log all exceptions that occur and rethrow the original, including the entire exception stack. Which code segment should you use for the above requirements? A) Catch(Exception ex) { ExceptionLogger.LogException(ex); throw; } B) Catch(Exception ex) { ExceptionLogger.LogException(ex); throw ex; } ``` ``` C) Catch(Exception) { ExceptionLogger.LogException(); throw; } D) Catch(Exception ) { ExceptionLogger.LogException(ex); throw ex; } ```

``` A) Catch(Exception ex) { ExceptionLogger.LogException(ex); throw; } ```

You are required to create an event source named mySource and a custom log named myLog on the server. You need to write the “Hello” information event to the custom log. Which code segment should you use? A) EventLog Log=new EventLog(){Source=”mySource”}; Log.WriteEntry(“Hello”,EventLogEntryType.Information); B) EventLog Log=new EventLog(){Source=”myLog”}; Log.WriteEntry(“Hello”,EventLogEntryType.Information); C) EventLog Log=new EventLog(){Source=”System”}; Log.WriteEntry(“Hello”,EventLogEntryType.Information); D) EventLog Log=new EventLog(){Source=”Application”}; Log.WriteEntry(“Hello”,EventLogEntryType.Information);

``` A) EventLog Log=new EventLog(){Source=”mySource”}; Log.WriteEntry(“Hello”,EventLogEntryType.Information); ```

You are required to create a program with the following requirements: In Debug Mode, console output must display Entering Release Mode. In Release Mode, console output must display Entering Debug Mode. Which code segment should you use? A) if DEBUG.DEFINED Console.WriteLine(“Entering Release Mode”); else Console.WriteLine(“Entering Debug Mode”); B) if RELEASE.DEFINED Console.WriteLine(“Entering Debug Mode”); else Console.WriteLine(“Entering Release Mode”); C) #if DEBUG Console.WriteLine(“Entering Release Mode”); #elif RELEASE Console.WriteLine(“Entering Debug Mode”); D) #if DEBUG Console.WriteLine(“Entering Debug Mode”); #elif RELEASE Console.WriteLine(“Entering Release Mode”);

C) #if DEBUG Console.WriteLine(“Entering Release Mode”); #elif RELEASE Console.WriteLine(“Entering Debug Mode”);

You are creating a library (.dll file) for your project. You need to make it a strongly typed assembly. What should you do? A) use the csc.exe/target:Library option when building the application B) use the AL.exe command line-tool C) use the aspnet_regiis.exe command line-tool D) use the EdmGen.exe command line-tool

B) use the AL.exe command line-tool

You are required to create a class “Load” with the following requirements: Include a member that represents the rate of a Loan instance. Allow an external code to assign a value to a rate member. Restrict the range of values that can be assigned to the rate member. To meet these requirements, how would you implement the rate member? A) public static property B) public property C) public static field D) protected field

B) public property

``` You are required to develop a method which can be called by a varying number of parameters. The method is called: A) Method Overriding B) Method Overloading C) Abstract Method D) Virtual Method ```

B) Method Overloading

``` You are working on an application where you need to encrypt highly sensitive data. Which algorithm should you use? A) DES B) Aes C) TripleDES D) RC2 ```

B) Aes

``` You need to create a unique identity for your application assembly. Which two attributes should you include for this purpose? A) AssemblyTitleAttribute B) AssemblyCultureAttribute C) AssemblyVersionAttribute D) AssemblyKeyNameAttribute E) AssemblyFileVersion ```

B) AssemblyCultureAttribute | C) AssemblyVersionAttribute

``` Which statement is used to remove the unnecessary resources automatically? A) using B) switch C) Uncheck D) Check ```

A) using

``` Which class is necessary to inherit while creating a custom attribute? A) Exception B) Attribute C) Serializable D) IEnumerable ```

B) Attribute

``` Which of the following interfaces is used to manage an unmanaged resource? A) IUnkown B) IEnumerable C) IComparable D) IDisposable ```

D) IDisposable

``` Which of the following interfaces is necessary to implement for creating a custom collection in C#? A) IUnkown B) IEnumerable C) IComparable D) IDisposable ```

B) IEnumerable

``` How would you parse a type to another in a way that it doesn’t generate an exception in a wrong conversion? A) as B) is C) out D) in ```

A) as

``` Which keyword is used to check or compare one type to another? A) as B) is C) out D) in ```

B) is

``` How should you create an extension method of an integer? A) static class ExtensionClass { public static void ExtensionMethod(this int i) { //do code } } B) static class ExtensionClass { public static void ExtensionMethod(int i) { //do code } } ``` ``` C) class ExtensionClass { public static void ExtensionMethod(this int i) { //do code } } D) static class ExtensionClass { public void ExtensionMethod(this int i) { //do code } } ```

``` A) static class ExtensionClass { public static void ExtensionMethod(this int i) { //do code } } ```

``` What should you use to encapsulate an array object? A) Indexer B) Property C) Event D) Private array ```

A) Indexer

``` Which of the following keywords is used for a dynamic variable? A) var B) dynamic C) const D) static ```

B) dynamic

``` Which of the following methods of assembly is used to get all types? A) GetTypes() B) GetType() C) ToTypeList() D) Types() ```

A) GetTypes()

How would you make sure the garbage collector does not release the object’s resources until the process completes? Which garbage collector method should you use? A) WaitForFullGCComplete() B) SuppressFinalize() C) collect() D) RemoveMemoryPressure()

B) SuppressFinalize()

``` You are developing an application that includes the following code segment: 01. class A { } 02. class B : A { } 03. class C 04. { 05. void Demo(object obj) { Console.WriteLine("Demo(obj)"); } 06. void Demo(C c) { Console.WriteLine("Demo(C)");} 07. void Demo(A a) { Console.WriteLine("Demo(A)");} 08. void Demo(B b) { Console.WriteLine("Demo(B)");} 09. 10. void Start() 11. { 12. object o = new B(); 13. Demo(o); 14. } 15. } You need to ensure that the Demo(B b) method runs. With which code segment should you replace line 13? A) Demo((B)o); B) Demo(new B(o)); C) Demo(o is B); D) Demo((A)o); ```

A) Demo((B)o);

How would you ensure that the class library assembly is strongly named? What should you do? A) Use the gacutil.exe command-line tool. B) Use the xsd.exe command-line tool. C) Use the aspnet_regiis.exe command-line tool. D) Use assembly attributes.

D) Use assembly attributes.

Suppose you are developing an application that includes an object that performs a long-running process. You need to ensure that the garbage collector does not release the object’s resources until the process completes. Which garbage collector method should you use? A) WaitForFullGCComplete() B) WaitForFullGCApproach() C) KeepAlive() D) WaitForPendingFinalizers()

C) KeepAlive()

``` You need to convert a date value entered in string format and you need to parse it into DateTime and convert it to Coordinated Universal Time (UTC). The code must not cause an exception to be thrown. Which code segment should you use? A) string strDate = ""; bool ValidDate = DateTime.TryParse(strDate, CultureInfo.CurrentCulture, DateTimeStyles.AdjustToUniversal | DateTimeStyles.AssumeLocal, out ValidatedDate); B) string strDate = ""; bool ValidDate = DateTime.TryParse(strDate, CultureInfo.CurrentCulture, DateTimeStyles.AssumeLocal, out ValidatedDate); C) bool validDate = true; try { ValidatedDate = DateTime.Parse(strDate); } catch { validDate = false; } ```

A) string strDate = ""; bool ValidDate = DateTime.TryParse(strDate, CultureInfo.CurrentCulture, DateTimeStyles.AdjustToUniversal | DateTimeStyles.AssumeLocal, out ValidatedDate);

``` How would you convert the following values? 01. float ft; 02. object o = ft; 03. 04. Console.WriteLine(i); You need to ensure that the application does not throw exceptions on invalid conversions. Which code segment should you insert at line 03? A) int i = (int)(float)o; B) int i = (int)o; C) int i = o; D) int i = (int)(double)o; ```

A) int i = (int)(float)o;

You are creating a class named Person. The class has a string property named FirstName. 01. class Person 02. { 03. public string FirstName 04. { 05. get; 06. set; 07. } 08. } The FirstName property value must be accessed and modified only by code within the Person class or within a class derived from the Person class. Which two actions should you perform? A) Replace line 05 with the protected get; B) Replace line 06 with the private set; C) Replace line 03 with the public string EmployeeType D) Replace line 05 with the private get; E) Replace line 03 with the protected string EmployeeType F) Replace line 06 with the protected set;

B) Replace line 06 with the private set; | E) Replace line 03 with the protected string

``` Suppose you’re creating an application that concatenates “1” value with a string for a million times. Which of the following codes would you use that minimize the completion time and concatenates the string for the millionth time? A) string str = ""; for (int i = 0; i < 1000000; i++) { str = string.Concat(str, "1"); } return str; B) var str = new StringBuilder(); for (int i = 0; i < 1000000; i++) { str.Append("1"); } return str.ToString(); C) var str = null; for (int i = 0; i < 1000000; i++) { str = str + "1"; } return str.ToString(); D) var str = null; for (int i = 0; i < 1000000; i++) { str += "1"; } return str.ToString(); ```

``` B) var str = new StringBuilder(); for (int i = 0; i < 1000000; i++) { str.Append("1"); } return str.ToString(); ```

Suppose you are developing an application that includes classes named Car and Vehicle and an interface named IVehicle. The Car class must meet the following requirements: It must either inherit from the Vehicle class or implement the IVehicle interface. It must be inheritable by other classes in the application. You need to ensure that the Car class meets the requirements. Which two code segments can you use to achieve this goal? A) sealed class Car : Vehicle { ... } B) abstract class Car: Vehicle { ... } ``` C) sealed class Car : IVehicle { ... } D) abstract class Car : IVehicle { } ```

``` B) abstract class Car: Vehicle { ... } ``` ``` D) abstract class Car : IVehicle { } ```

Suppose you are creating an application that manages the information of persons. The application includes a class named Person and a method named Save. The Save() method must be strongly typed. It must allow only types inherited from the Person class that use a constructor that accepts no parameters. You need to implement the Save() method. Which code segment should you use? A) public static void Save(T target) where T: new(), Person { ... } B) public static void Save(T target) where T: Person { ... } C) public static void Save(T target) where T: Person, new() { ... } D) public static void Save(Person person) { ... }

``` C) public static void Save(T target) where T: Person, new() { ... } ```

``` Suppose you are developing an application that uses the following C# code: 01. public interface IPerson 02. { 03. string Name { get; set; } 04. } 05. 06. void Demo(object obj) 07. { 08. 09. if(person != null) 10. { 11. System.Console.WriteLine(person.Name); 12. } 13. } The Demo() method must not throw any exceptions when converting the obj object to the IPerson interface or when accessing the Data property. You need to meet the requirements. Which code segment should you insert at line 08? A) var person = (IPerson)obj; B) dynamic person = obj; C) var person = obj is IPerson; D) var person = obj as IPerson; ```

D) var person = obj as IPerson;

``` You are developing an application. The application converts a Person object to a string by using a method named WriteObject. The WriteObject() method accepts two parameters: a Person object and an XmlObjectSerializer object. The application includes the following code: 01. public enum Gender 02. { 03. Male, 04. Female, 05. Others 06. } 07. [DataContract] 08. public class Person 09. { 10. [DataMember] Chapter 16 ■ Practice Exam Questions 434 11. public string Name { get; set; } 12. [DataMember] 13. public Gender Gender { get; set; } 14. } 15. void Demo() 16. { 17. var person = new Person { Name = "Ali", Gender = Gender.Male }; 18. Console.WriteLine(WriteObject(person, 19. 20. )); 21. } You need to serialize the Person object as a JSON object. Which code segment should you insert at line 19? A) new DataContractSerializer(typeof(Person)) B) new XmlSerializer(typeof(Person)) C) new NetDataContractSenalizer() D) new DataContractJsonSerializer(typeof(Person)) ```

D) new DataContractJsonSerializer(typeof(Person))

You’re creating an application that receives a JSON data in the following format: { "Name" : "Ali", "Age" : "22", "Languages": ["Urdu", "English"] } The application includes the following code segment: 01. public class Person 02. { 03. public string Name { get; set; } 04. public int Age { get; set; } 05. public string[] Languages { get; set; } 06. } 07. public static Person ConvertToPerson(string json) 08. { 09. var ser = new JavaScriptSerializer(); 10. 11. } You need to ensure that the ConvertToName() method returns the JSON input string as a Name object. Which code segment should you insert at line 10? A) Return ser.ConvertToType(json); B) Return ser.DeserializeObject(json); C) Return ser.Deserialize(json); D) Return (Person)ser.Serialize(json);

C) Return ser.Deserialize(json);

``` You are developing an application that includes the following code segment: interface ILion { void Run(); } interface IMan { void Run(); } ``` ``` You need to implement both Run() methods in a derived class named Animal that uses the Run() method of each interface. Which two code segments should you use? A) var animal = new Animal(); ((ILion, IMan)animal).Run(); B) class Animal : ILion, IMan { public void IMan.Run() { ... } public void ILion.Run() { ... } } C) class Animal : ILion, IMan { void IMan.Run() { ... } void ILion.Run() { ... } } D) var animal = new Animal(); ((ILion)animal).Run(); ((IMan)animal).Run(); E) var animal = new Animal(); animal.Run(ILion); animal.Run(IMan); F) var animal = new Animal(); animal.Run(); ```

``` B) class Animal : ILion, IMan { public void IMan.Run() { ... } public void ILion.Run() { ... } } ``` D) var animal = new Animal(); ((ILion)animal).Run(); ((IMan)animal).Run();

Suppose you’re creating an application; in the application you need to create a method that can be called by using a varying number of parameters. What should you use? A) derived classes B) interface C) enumeration D) method overloading

D) method overloading

Suppose you’re creating an application that needs a delegate that can hold a reference of a method that can return bool and accept an integer parameter. How would you define that delegate? A) delegate bool myDelegate(int i, int j); B) delegate bool (int i, int j); C) delegate myDelegate(int i, int j); D) delegate bool myDelegate(int i);

A) delegate bool myDelegate(int i, int j);

``` Which property or method of task can be used as an alternative of the await keyword? A) Result B) Wait() C) WaitAll() D) Delay() ```

A) Result

``` You’re creating an application that has many threads that run in parallel. You need to increment an integer variable “i". How would you increment it in an atomic operation? A) int i = 0; Interlocked.Increment(ref i); B) int i = 0; Interlocked.Increment(i); ``` ``` C) int i = 0; i++; D) int i = 0; Interlocked.Increment(out i); ```

A) int i = 0; Interlocked.Increment(ref i);

``` Suppose you’re creating a method that threw a new exception but it also threw an inner exception. See the following code: 01. private void myMethod(int i) 02. { 03. try 04. { 05. ... 06. } 07. catch (ArgumentException ex) 08. { 09. 10. } 11. } You must preserve the stack trace of the new exception and also throw the inner exception; which code statement would you use in line 09? A) throw ex; B) throw new Exception("Unexpected Error", ex); C) throw; D) throw new Exception(ex) ```

B) throw new Exception("Unexpected Error", ex);

``` Suppose you’re developing an application and you want to make a thread-safe code block for execution. Which of the following code blocks would you use to write code? A) object o = new object(); lock (o) { ... } B) object o = new object(); lock (typeof(o)) { ... } Chapter 16 ■ Practice Exam Questions 429 C) lock (new object ()) { ... } D) lock { ... } ```

``` A) object o = new object(); lock (o) { ... } ```

``` Which of the following is the right syntax for using an asynchronous lambda expression? A) Task task = async () => { … }; B) Task task = async () => { … }; C) Func task = async () => { … }; D) Action task = async (t) => { … }; ```

C) Func task = async () => { … };

``` When running a long-running asynchronous operation that returns a value, which keyword is used to wait and get the result? A) await B) yield C) return D) async ```

A) await

``` Which of the following collections is a thread-safe? A) Dictionary B) Stack C) ConcurrentDictionary D) Queue ```

C) ConcurrentDictionary

``` Which keyword is useful for returning a single value from a method to the calling code? A) yield B) return C) break D) continue ```

A) yield

``` Foreach loop can only run on: A) anything B) collection C) const values D) static values ```

B) collection

``` In a switch statement, which keyword would you use to write a code when no case value satisfies? A) else B) default C) return D) yield ```

B) default

``` How would you chain the execution of a task so that every next task runs when the previous task finishes its execution? Which method you would use? A) task.ContinueWith() B) Task.Wait() C) Task.Run() D) Thread.Join() ```

A) task.ContinueWith()

``` Which of the following methods is useful for holding the execution of a main thread until all background tasks are executing? A) Thread.Sleep() B) Task.WaitAll() C) Task.Wait() D) Thread.Join() ```

B) Task.WaitAll()

``` Which of following methods is accurate for holding the execution of a running task for a specific time? A) Thread.Sleep() B) Task.Delay() C) Task.Wait() D) Task.WaitAll() ```

B) Task.Delay()

``` When handling an exception, which block is useful to release resources? A) try B) catch C) finally D) lock ```

C) finally

``` Which keyword is used to prevent a class from inheriting? A) sealed B) lock C) const D) static ```

A) sealed

``` await keyword can only be written with a method whose method signature has: A) static keyword B) async keyword C) lock keyword D) sealed keyword ```

B) async keyword

``` Which of the following loops is faster? A) for B) do C) Parallel.for D) foreach ```

C) Parallel.for

``` Which of the following keywords is useful for ignoring the remaining code execution and quickly jumping to the next iteration of the loop? A) break; B) yield; C) jump; D) continue; ```

D) continue;

``` You need to reference a method which returns a Boolean value and accepts two int parameters. Which of the following delegates would you use? A) Func func; B) Action act; C) Func func; D) Action act; ```

A) Func func;

``` You’re creating an application that contains the following code: class Test { public event Action Launched; } class Program { static void Main(string[] args) { Test t = new Test(); } } How would you subscribe a Launched event in the Main method to the “t” instance? A) t.Launched += ()=>{..}; B) t.Launched = ()=>{..}; C) t.Launched -= ()=>{..}; D) t.Launched = t.Launched + ()=>{…}; ```

A) t.Launched += ()=>{..};

``` How do you throw an exception so the stack trace preserves the information? A) throw; B) throw new Exception(); C) throw ex; D) return new Exception(); ```

A) throw;

``` To create a custom exception, which class is required to be inherited? A) SystemException B) System.Exception C) System.Attribute D) Enumerable ```

B) System.Exception

An exception is handled on a method which mathematically calculates numbers. The method contains the following catch blocks: 01. 02. catch(ArithmeticException e) { Console.WriteLine("Arithmetic Error"); } 03. 04. catch (ArgumentException e) { Console.WriteLine("Invalid Error"); } 05. 06. catch (Exception e) { Console.WriteLine("General Error"); } 07. You need to add the following code to the method: catch (DivideByZeroException e) { Console.WriteLine("Divide by Zero"); } At which line should you insert the code? A) 01 B) 03 C) 05 D) 07

A) 01

A method name LongRunningMethod(CancellationTokenSource cts), takes a cancellation token source and performs a long-running task. If the calling code requests cancellation, the method must Cancel the longrunning task and set the task status to TaskStatus.Canceled. Which of the following methods should you use? A) throw new AggregateException(); B) ct.ThrowIfCancellationRequested() ; C) cts.Cancel(); D) if (ct.IsCancellationRequested) return;

B) ct.ThrowIfCancellationRequested() ;

``` Which class should you preferably use for tracing in Release Mode? A) Debug B) Trace C) TraceSource D) All of the above ```

C) TraceSource

``` To build a project you need a PDB file of: A) Previous build version B) Any build version C) No need of PDB file D) Same build version ```

D) Same build version

``` Which method is the easiest way of finding the problem if you have no idea what it is? A) Using Profiler B) Profiling by Hand C) Using Performance Counter D) Debugging ```

A) Using Profiler

A) sn -k {assembly_name}.snk

``` Which of the following methods is used for getting the information of the current assembly? A) Assembly. GetExecutingAssembly(); B) Assembly.GetExecutedAssembly(); C) Assembly.GetCurrentAssembly(); D) Assembly.ExecutingAssembly(); ```

A) Assembly. GetExecutingAssembly();

A) BindingFlags.NonPublic | BindingFlags.Instance

``` The application needs to encrypt highly sensitive data. Which algorithm should you use? A) DES B) Aes C) TripleDES D) RC2 ```

B) Aes

B) HMACSHA256

Salt Hashing is done by: A) Merging data with random value and perform cryptography. B) Merging data with random value and perform cryptanalysis. C) Merging data with random value and perform encryption. D) Merging data with random value and perform hashing

D) Merging data with random value and perform hashing

``` You want to retrieve data from Microsoft Access 2013, which should be read-only. Which class you should use? A) SqlDataAdapter B) DbDataAdapter C) OleDbDataReader D) SqlDataReader ```

C) OleDbDataReader

``` Suppose you created the ASMX Web Service named SampleService. Which class you would use to create the proxy for this service? A) SampleServiceSoapClient B) SampleService C) SampleServiceClient D) SampleServiceSoapProxy ```

A) SampleServiceSoapClient

Choose the correct code snippet/snippets for insert query (insert code snippet of C#, syntax vise): A) SqlConnection con=new SqlConnection(“ConectionString”); SqlCommand cmd=new SqlCommand(insertQuery,con); Con.open(); Cmd.ExecuteNonQuery(); Con.close(); B) Using(SqlConnection con=new SqlConnection(“ConectionString”)) { SqlCommand cmd=new SqlCommand(insertQuery,con); Cmd.ExecuteNonQuery(); } C) SqlConnection con=new SqlConnection(“ConectionString”); Using( SqlCommand cmd=new SqlCommand(insertQuery,con)) { Con.open(); Cmd.ExecuteNonQuery(); } D) Using(SqlConnection con=new SqlConnection(“ConectionString”)) { SqlCommand cmd=new SqlCommand(insertQuery,con); Con.Open(); Cmd.ExecuteNonQuery(); }

A) SqlConnection con=new SqlConnection(“ConectionString”); SqlCommand cmd=new SqlCommand(insertQuery,con); Con.open(); Cmd.ExecuteNonQuery(); Con.close(); D) Using(SqlConnection con=new SqlConnection(“ConectionString”)) { SqlCommand cmd=new SqlCommand(insertQuery,con); Con.Open(); Cmd.ExecuteNonQuery(); }

``` You are developing an application that retrieves Person type data from the Internet using JSON. You have written the following function for receiving the data so far: serializer.Deserialize(json); Which code segment should you use before this function? A) DataContractJsonSerializer serializer = new DataContractJsonSerializer(typeof(Person)); B) DataContractSerializer serializer = new DataContractSerializer(typeof(Person)); C) JavaScriptSerializer serializer = new JavaScriptSerializer(); D) NetDataContractSerializer serializer = new NetDataContractSerializer(); ```

C) JavaScriptSerializer serializer = new JavaScriptSerializer();

``` Question 2 You need to store a large amount of data in a file. Which serializer would you consider better? A) XmlSerializer B) DataContractSerializer C) DataContractJsonSerializer D) BinaryFormatter E) JavaScriptSerializer ```

D) BinaryFormatter

``` You want to serialize data in Binary format but some members don’t need to be serialized. Which attribute should you use? A) XmlIgnore B) NotSerialized C) NonSerialized D) Ignore ```

C) NonSerialized

C# Certification Flashcards

70-483 Certification Exam Review (892 cards)