C# Object Model Flashcards
1
Q
- IDE
- UI
- UWP
- XML
- XAML
A
- Integrated Development Environment
- User Interface
- Universal Windows Platform
- Extensible Markup Language
- Extensible Application Markup Language
2
Q
Assemblies
A
- Libraries of compiled code
- Located in the References folder
3
Q
- //
- (/*) and (*/)
A
- Comments
- Comments on multiple lines. Opening and closing statements
4
Q
- using System;
- using System.Collections.Generic;
- using System.Linq;
- using System.Text;
- using System.Threading.Tasks;
A
Using directives that refer to namespaces
5
Q
using Windows.UI.Popups;
A
Contains the MessageDialog class
6
Q
- Syntax
- Semantics
A
- Relates to format and construction
- Relates to what statements do
7
Q
Message Box
A
Console.WriteLine();
8
Q
- Assign a value to a float variable
- Assign a value to a long variable
- Assign a value to a decimal variable
A
- Add F after the value
- Add L after the value
- Add M after the value
9
Q
- Convert a string value to an integer
- Convert a string value to a double
- Convert a numeric value to a string
A
- Int.Parse();
- Double.Parse();
- ToString();
10
Q
String Interpolation
A
- $”String1 {String2}”
- $”{String1}{String2}”
11
Q
- Remainder (Modulus) operator
- Not operator
- Equality operator
- And operator
- OR operator
A
- %
- !
- ==
- &&
- ||
12
Q
Associativity
A
- *, / → left to right
- = → right to left
13
Q
Void
A
Does not return a value
14
Q
Cause immediate exit from a void method
A
Write return; with no expression
15
Q
Expression-bodied method
A
- Methods with a single line of code
- Example: void showResult(int answer) => Console.Writeline($”The answer is {answer}”);
16
Q
C# term for variable defined by a class
A
Field
17
Q
In a method, you must declare a variable before you can use it
A
In a class, you can declare a field can be declared after the statements that require it
18
Q
Optional parameters
A
Simply assign them a default value
19
Q
Short circuiting
A
- When the first expression of a && statement is false
- When the first expression of a || statement is true
20
Q
Switch allowed variables
A
Int, char and string variables
21
Q
SystemException
A
- FormatException
- OverflowException
22
Q
Exception filters
A
Example:
catch (Exception e) when (e.GetType() != typeof(System.OutOfMemoryException))
23
Q
Refer to the minimum or maximum value of and int
A
- int.MinValue
- int.MaxValue
24
Q
Integer arithmetic overflow checking (int or long)
A
- checked
- {…
- }
- unchecked
- {…
- }
25
Throwing an exception
throw new *ExceptionType* ("Message")
26
Create an instance of a class
* Requires the new keyword
* Example:
* Circle c;
* c = new Circle();
27
Variables declared in a method are not initialized by default
Variables declared in a class are automatically initialized to 0, false or null
28
Every class must have a constructor
* It must have the same name as the class
* It is public
* It initializes the fields
29
Partial class
A class that has been split into two files
30
this keyword
Refers to the field in the object
31
Static methods
* Can be accessed without creating an instance of the class in which they are contained
* Can not access instance methods or instance fields defined in that same class
* Are available through the lifetime of an application
32
public static fields
Are shared by all the objects of a class and can be accessed from outside the class
33
static classes
* Can only contain static members
* Cannot contain any instance data or methods
* Are accessed directly with the name of the class (and not the object as it is usually the case)
34
using static *class name*
Allows you to access a static member of a class without specifying the class name
35
Anonymous class
* Can contain only public fields
* All fields must be initialized and cannot be static
* Example: var *name* = new { Amount = 108, Message = "*string*" };
36
Value types
* int
* float
* double
* char
37
Reference types
* class
* string
* object
* array
38
Passing a value type as a parameter
A copy of the variable is made and the original one is unaffected
39
Passing a reference type as a parameter
The original value of the variable, class or object is modified
40
Nullable types
* Use ? to declare a nullable value type
* Example: int? i = null;
* Use !i.HasValue to test if the variable is null
41
Passing a parameter as *ref*
* Passes the parameter as a reference rather than a copy
* Example:
* name (ref i)
* static void *name* (ref int i)
42
Passing a parameter as *out*
* Passes the parameter as a reference rather than a copy and initializes it
* Example:
* name (out i)
* static void name (out int i)
43
C# enforces the assignment of values to variables
Variables can't be read if they have not been initialized
44
Stack and heap memory
* Stack
* Comes into existence for the execution of a method and is then released
* Contains value types
* Heap
* Comes into existence with the *new* keyword. Holds objects that are created
* Contains reference types and nullable types
45
Boxing
* Copying an item from the stack to the heap
* Example:
* int i = 10;
* object x = i;
* Note: if you modify the value on the heap, the value on the stack will not change and vice versa
46
Cast
* Is used to verify if an object contains the specified variable type
* Example:
* int i = 10;
* object x = i;
* i = (int)x;
47
is operator
Is used to test if a variable is of a certain type
48
as operator
* Is used to cast a variable as a certain type
* Example:
* object x = AA
* *CustomObject* test = x as *CustomObject*
49
Enumeration type
* Contains a limited set of symbolic names
* Example:
* enum Season { Spring, Summer, Fall, Winter }
50
Structure type
* Acts like a class but is stored in the stack
* The compiler always generates a default constructor for structures
51
How to insert a backslash
(C# assumes that every backslash is the start fo a special character)
* Use two backslash: \\
* Put the @ character before the entire string: @"*string*"
