C# types can be divided mainly into two categories: value types and reference types. In this article, we would be having a closer look at these two types.

Value Types

• Most of the c# built-in types such as numeric types, char types and boolean types are value types.

• custom structs and enum types are also value types.

• content of a value-type variable or constant is simply a value.

• The assignment operator always copies the value.

    int a = 10;
    int b = 7;
    b = a;   // copies the value of a into b
    Console.WriteLine(" a = {0}, b = {1}", a, b);  //  a = 10, b = 10
    a = 15;  // b won't change
    Console.WriteLine(" a = {0}, b = {1}", a, b);  //  a = 15, b = 10
  

custom value types

custom value types can be created using struct or enum .

 public struct Point { public int X; public int Y; }
 Point p1 = new Point();
 p1.X = 7;
 Point p2 = p1; // Assignment causes copy
 Console.WriteLine (p1.X); // 7
 Console.WriteLine (p2.X); // 7

 p1.X = 9; // Change p1.X
 Console.WriteLine (p1.X); // 9
 Console.WriteLine (p2.X); // 7

Reference Types

• A reference type has two parts: an object and the reference to that object.

• content of a reference-type variable or constant is a reference to an object that contains the value.

• a class type, an interface type, an array type, a delegate type, or the dynamic type are all reference types.

public class Point { public int X, Y; }
Point p1 = new Point();
p1.X = 7;
Point p2 = p1; // Copies p1 reference
Console.WriteLine (p1.X); // 7
Console.WriteLine (p2.X); // 7
p1.X = 9; // Change p1.X
Console.WriteLine (p1.X); // 9
Console.WriteLine (p2.X); // 9

value types and reference types and null

• null can be assigned to reference types without any issue. assigning null to a reference type indicates that the reference points at nothing.

• a value type cannot have null [Except Nullable Value types ]

  int x = null // compile time error

That's it for this article. Thanks for reading it. Please share your thoughts into comment section.