C#

Question 1

class labeled ‘abstract’ (3 things)

Answer 1

class is intended only to be base class of other classes; can’t be instantiated; a class dervied from abstract class must implement all abstract members

Question 2

method or property labeled ‘abstract’ (3 things)

Answer 2

method does not have implementation; only allowed in abstract class; no {}, goes right to ;

Question 3

Cast that returns null instead of raising an exception

Answer 3

EXPRESSION as TYPE

Question 4

How to call method on base class that has been overridden?

Answer 4

Use base.method();

Question 5

How to call the base class’s constructor from the derived class constructor?

Answer 5

public class DerivedClass(int i) : base(int i) {…}

Question 6

Data type for unsigned 8 bit integer

Answer 6

byte

Question 7

Data type for unicode 2 byte character

Answer 7

char

Question 8

How to raise an exception on code that could overflow?

Answer 8

checked { block; } or checked(expression)

Question 9

Data type for numeric 16 byte

Answer 9

decimal

Question 10

Suffix for literal of type decimal

Answer 10

m

Question 11

For a generic (template), how to get an initialization value for the type?

Answer 11

= default(T);

Question 12

How to create a function pointer?

Answer 12

delegate returntype name();

Question 13

Suffix for literal of type double

Answer 13

d

Question 14

How to declare a variable of nullable bool type?

Answer 14

bool? x;

Question 15

How to declare an enum with a non-int underlying type?

Answer 15

enum EnumName : newtype {value, value};

Question 16

How to declare an explicit cast conversion operator?

Answer 16

public static explicit operator NewTypeName(OldTypeName x) { return new NewTypeName(…) };

Question 17

How to declare an implicit cast conversion operator?

Answer 17

public static implicit operator NewTypeName(OldTypeName x) { return new NewTypeName(…) };

Question 18

What does extern method marking do?

Answer 18

specifies the implementation of the method is external

Question 19

Why use finally in try catch?

Answer 19

Clean up in case the catch returns or throws a new exception

Question 20

How to pin the location of a variable in unsafe code?

Answer 20

fixed (int* x = pinnedvar)

Question 21

Suffix for literal of type float

Answer 21

f

Question 22

How to redirect to a different switch case?

Answer 22

goto case 5;

Question 23

How to declare an interface?

Answer 23

interface Iname { void func(); }

Question 24

How to declare something as only accessible in this assembly?

Answer 24

internal

Question 25

How to check if object has a type or has a derivation of a type

Answer 25

if (obj is myObj) { }

Question 26

How to block a critical section that can only be run by one thread at a time?

Answer 26

Object thisLock = new Object(); lock(thisLock) { statements; }

Question 27

Suffix for literal of type long

Answer 27

L

Question 28

singed integer types (1 byte, 2 byte, 4 byte, 8 byte)

Answer 28

sbyte, short, int, long

Question 29

In derived class, new vs override method?

Answer 29

If reference to base class is used, with NEW the base class is called, with OVERRIDE the derived class is called

Question 30

Generic class constraint requiring a constructor with no parameters

Answer 30

class ClassName where T : new() {}

Question 31

Overload the addition operator

Answer 31

public static ReturnType operator +(Type a, Type b) { }

Question 32

Method parameter out vs ref

Answer 32

ref requires initialization of the variable first

Question 33

How to expect multiple parameters of any type?

Answer 33

void foo(params object[] list) { }

Question 34

What does readonly modifier do?

Answer 34

Member variable can only be set in declaration or in a constructor of that class

Question 35

unsigned integer types (1 byte, 2 byte, 4 byte, 8 byte)

Answer 35

byte, ushort, uint ulong

Question 36

What does sealed modifier on a class do?

Answer 36

Stops inheritence from the class

Question 37

What does sealed modifier on a method do?

Answer 37

Stops overriding of that method

Question 38

fractional data types (4 byte, 8 byte, 16 byte)

Answer 38

float, double, decimal

Question 39

How to allocate a block of memory on the stack (in unsafe code)?

Answer 39

int* block = stackalloc int[100];

Question 40

What does static modifier mean on a class? (2 things)

Answer 40

Only one instance exists; all members must be static

Question 41

What does static modifier mean on a method?

Answer 41

Method must be called from class name, not instance name

Question 42

Three uses of keyword this?

Answer 42

Differentiate between params and members, pass instance to another func, indexer

Question 43

How to suppress overflow checking for a block of code?

Answer 43

unchecked { block; } or unchecked(expression);

Question 44

How to designate a block of code to allow pointers?

Answer 44

unsafe { block; } or unsafe void foo() { };

Question 45

How to create an alias for a class?

Answer 45

using X as namespace.ClassName;

Question 46

How to temporarily use a variable in a block of code?

Answer 46

using (variable = new constructor()) { }

Question 47

What does modifier volatile do?

Answer 47

indicates a member variable could be modified by multiple threads

Question 48

What are add and remove keywords used for?

Answer 48

when client code subscribes or unsubscribes from an event (structured like property)

Question 49

typeof vs GetType vs is

Answer 49

typeof takes a type name specified at compile time, GetType returns runtime type of instance, is returns true if instance in inheritence tree

Question 50

How to declare variable that could have any type?

Answer 50

dynamic

Question 51

How to split a class across multiple files?

Answer 51

use the modifier partial

Question 52

What does partial modifier mean for a method?

Answer 52

separates signature from implementation, like .cpp and .h files. If no implementation, signature is removed

Question 53

How to declare function-scope variable with implicit type?

Answer 53

var x = 10;

Question 54

How to specify generic, where the type supports a specific interface?

Answer 54

public class MyClass where T:IComparable {}

Question 55

Event sequence when a button on a winform is clicked?

Answer 55

Enter GotFocus MouseDown MouseUp Click

Question 56

Show() vs ShowDialog()

Answer 56

ShowDialog() is modal

Question 57

Anchoring vs docking

Answer 57

Anchoring size is constant, docking location is constant

Question 58

What is an asynchronous callback delegate?

Answer 58

Function gets passed in, but may not be called before the function exits, could be called after

Question 59

What is covariance in delegates?

Answer 59

Permits a method to have a more derived return type than what is defined in the delegate

Question 60

Dispose vs Finalize vs Destructor

Answer 60

Finalize = Destructor, Dispose should be called by your code