Identifiers

 In programming languages, identifiers are used for identification purposes. Or in other words, identifiers are the user-defined name of the program components. In C#, an identifier can be a class name, method name, variable name, or label.

Example:

public class DVU {

    static public void Main ()

    {

          int x;

    }

}

Here the total number of identifiers present in the above example is 3 and the names of these identifiers are:

DVU: Name of the class

Main: Method name

x: Variable name

Rules for defining identifiers in C#:

There are certain valid rules for defining a valid C# identifier. These rules should be followed, otherwise, we will get a compile-time error.

 The only allowed characters for identifiers are all alphanumeric characters([A-Z], [a-z], [0-9]), ‘_‘ (underscore). For example “geek@” is not a valid C# identifier as it contain ‘@’ – special character.

Identifiers should not start with digits([0-9]). For example “123geeks” is not valid in the C# identifier.

Identifiers should not contain white spaces.

 Identifiers are not allowed to use as keywords unless they include @ as a prefix. For example, @as is a valid identifier, but “as” is not because it is a keyword.

C# identifiers allow Unicode Characters.

C# identifiers are case-sensitive.

C# identifiers cannot contain more than 512 characters.

Identifiers do not contain two consecutive underscores in their name because such types of identifiers are used for the implementation.

Example:

 // Simple C# program to illustrate identifiers

using System;

 class DVU {

     // Main Method

    static public void Main()

    {

         // variable

        int a = 10;

        int b = 39;

        int c;

         // simple addition

        c = a + b;

        Console.WriteLine("The sum of two number is: {0}", c);

    }

}