C#

Question 1

What is a statically typed language?

Answer 1

Static typing is where the type is bound to the variable. Types are checked at compile time. C# and Java are statically typed languages.

Question 2

What is a dynamically typed language?

Answer 2

Dynamic typing where the type is bound to the value. Types are checked at run time. PHP and JavaScript are dynamically typed languages.

Question 3

What is a strongly typed language?

Answer 3

Strongly typed languages will not allow automatic conversion from one type to another. It does not allow for type coercion. Python is a strongle typed language.

Question 4

What is a weakly typed language?

Answer 4

Weakly typed languages do allow for automatic conversion from one type to another. It allows for type coercion. JavaScript is a weakly typed language.

Question 5

What does type safe mean?

Answer 5

Type safety is the idea that you can only interact with an object in ways that are allowed by that object. For example, C# prevents you from interacting with a string type as if it were an integer type.

Question 6

What does memory safe mean?

Answer 6

Memory safety is a property of programming languages where all memory access is well defined. Most programming languages in use today are memory safe because they use some form of garbage collection.

Question 7

What is a value type?

Answer 7

A value type is the actual value. If it is declared within the body of a method then it is placed on the stack. If a value type is declared inside a reference type then is will be placed within the reference type on the heap.

Question 8

What is a reference type?

Answer 8

A reference type’s value is stored in the Heap. It is accessed by a pointer. The pointer is stored in the Stack which points to an address in the Heap where the real value is stored.

Question 9

In memory what is the Stack?

Answer 9

The Stack keeps track of what’s executing in the code. It is self maintaining and takes care of its own memory management.

Question 10

In memory what is the Heap?

Answer 10

The Heap’s purpose is to hold data, so anything in the the Heap can be accessed at any time. The heap contains Reference Type values. It is garbage collected.

Question 11

What is a namespace?

Answer 11

A namespace is a way to logically arrange classes, interfaces, structs, etc. into their own named space. It’s used to provide context for the compiler for all named information in the program.

Question 12

What is a using statement?

Answer 12

It explicitly tells the compiler that you’ll be using a certain namespace in the program. A developer can avoid having to fully qualify classes with the namespace in every instance of typing it.

Question 13

What is an access modifier?

Answer 13

They are keywords that define the accessibility of a member, class or datatype in a program. It can restrict unwanted access by external programs or classes.

Question 14

What is the default access modifier for a class?

Answer 14

internal

Question 15

What is the default access modifier for a type member?

Answer 15

private

Question 16

What is the internal access modifier?

Answer 16

The type of member can only be accessed by code in the same assembly.

Question 17

What is the private access modifier?

Answer 17

The type or member can only be accessed by code in the same class or struct.

Question 18

What is the protected access modifier?

Answer 18

The type or member can only be accessed by code in the same class, or in a class that is derived from that class.

Question 19

What is the public access modifier?

Answer 19

The type or member can be access by any other code in the same assembly or another assembly that references it.

Question 20

What is the protected internal access modifier?

Answer 20

The type or member can be accessed by any code in the same assembly or from within a derived class in another assembly.

Question 21

What is the private protected access modifier?

Answer 21

The type or member can only be accessed with its declaring assembly by code in the same class or in a type that is derived from that class.

Question 22

What is a statement?

Answer 22

Statements are written using C# Keywords and Expressions. They end in a semicolon or curly braces.

Question 23

What is an expression?

Answer 23

Expressions are constructed using operators and operands. They usually result in a value.

Question 24

What is the Common Language Runtime (CLR)?

Answer 24

The execution engine is called the Common Language Runtime. It consists of the Just-In-Time compiler, Runtime Type Safety, and Garbage Collection

Question 25

What is the .NET Base Class Libraries (BCL)?

Answer 25

It is part of the .NET Framework that provides library support to the CLR to work properly.

Question 26

What is Common Intermediate Language (CIL)?

Answer 26

C# is compiled into CIL using the Roslyn compiler. The dotnet build command uses MSBuild. MDBuild uses the Roslyn compiler. CIL is the Assembly. This could be a DLL or EXE file.

Question 27

What is Just-In-Time compiler (JIT)?

Answer 27

The JIT compiles the CIL into machine code, as needed. The machine code is then executed by the CPU.

Question 28

What are the Integer Types in C#?

Answer 28

Integer types are value types.
Signed: sbyte, short, int, long
Unsigned: byte, ushort, uint, ulong

Question 29

What are the Decimal Types in C#?

Answer 29

Decimal types are value types.
floating decimal point: float, double
fixed decimal point: decimal

Question 30

What are the other Value Types in C#?

Answer 30

enum
char
bool
struct

Question 31

What are the Reference Types in C#?

Answer 31

String
Arrays
Class
Delegates

Question 32

What is immutable in C#?

Answer 32

Strings are immutable. If changes are made to a string object then the old instance will be discarded and a new instance will be created in to hold the new value.

Question 33

What happens when you pass a value type into a method?

Answer 33

A new copy of the variable will be created for the method. If the value is changed in the method, it will not affect the variable value.

Question 34

What happens when you pass a reference type into a method?

Answer 34

A new copy will not be created, instead a copy of the address in memory will be passed into the method. Changes to the passed in object will change the original object.

Question 35

What is Boxing in C#?

Answer 35

It is used to store value types on the garbage collected heap. It is an implicit conversion of a value type or to any interface type implemented by this value type.

Question 36

What is Unboxing in C#?

Answer 36

It is an explicit conversion from the type object to a value type.