.Net , SQL & React : C# Basic Questions and Answers

1. String Vs String builder

String	String Builder
Inmutable(unable to be changed.)	Mutable
Object reacted for each string object separately in memory and it will create plenty of memory so it may be run slow	Use less memory and run faster

2. Read-only Vs Const Vs Static

3. Abstract Vs Interface

4. Ref Vs Out

Ref

Out

The ref keyword is used to pass an argument as a reference.
This means that when the value of that parameter is changed in the method.
It gets reflected in the calling method.
An argument that is passed using a ref keyword must be initialized in the calling method before it is passed to the called method.

The out keyword is also used to pass an argument like the ref keyword.
But the argument can be passed without assigning any value to it.
An argument that is passed using an out keyword must be initialized in the called method before it returns back to the calling method.

5. For Vs Foreach

6.Type of Constructor

Default Constructor:

public Person()

{

Name = "John Doe";

Age = 30;

}

Parameterized Constructor:

Scholar(String name, int id)

{

this.name = name;

this.id = id;

}

Copy Constructor:

class Scholars

{

private string month;

private int year;

// Declaring Copy constructor

public Scholars(Scholars s)

{

month = s.month;

year = s.year;

}

// Instance constructor

public Scholars(string month, int year)

{

this.month = month;

this.year = year;

}

Private Constructor:

A constructor is referred to as a private constructor if it was created with the private specifier. This class cannot be derived from by any other classes, nor can an instance of this class be created.

public class Scholars

{

// Declare a private constructor

private Scholars()

{

}

// Declare a static variable field

public static int count_scholars;

// Declare a static method

public static int scholars_Count()

{

return ++count_scholars;

}

Static Constructor:

Static constructors are designed to be used just once to initialize static class fields or data.

class scholars {

// It is invoked before the first

// instance constructor is run.

static scholars()

{

// The following statement produces

// the first line of output,

// and the line occurs only once.

Console.WriteLine("Static Constructor");

}

7. SOLID Principle

8. Delegate with Example

9. Type of Routing

Conventional Routing and Attributal Routing

10. Sealed Class Vs Static Class

11. MVC filter

After MVC 5 Authentication filter is also available

12. Action Results

13. Tempdata - Peek Vs Keep

Not Read
Normal Read
Read and Keep
Peek and Read

Refer the following page (https://www.codeproject.com/Articles/818493/MVC-Tempdata-Peek-and-Keep-confusion)

14. As Vs Is

IS keyword is helpful to check if the object is that type or not.
AS keyword is helpful too if we want to convert one type to another type.
IS keyword type is boolean and AS keyword is not a boolean type.
The operator returns true if the given object is of the same type whereas as operator returns the object when they are compatible with the given type.

15. Extenstion Methods

16. Overloading (Compile-Time) Vs Overrding(Run-Time)

17.Generic Collections(Array, IDictory,List ,IList)

Generic is a type to be specified later. They are instantiated when needed for a specific type provided as parameters. In other words, a Generic allows you to write a class or method that can work with any data type(System.Collection.Generic namespace)