Enum in C# Programming

In this blog, we will discuss Enum in C# .NET & some Rules for Enum.

Description:

• We can create our own set of named constants by using enumerations.
• Keyword enum is used to declare enumerations.

Syntax

enum name_of_enum {enumeration list };

Example

class demo_enum
{
    enum my_enum
    {
        a, b, c, d, e, f
    };
    public static void Main()
    {
        my_enum i; // declare an enum variable
        for (i = my_enum.a; i < my_enum.f; i++) Console.WriteLine(" {0}", i + " has value of: " + (int) i);
        Console.WriteLine();
        Console.ReadKey();
    }
}

Output:



Some Rules for Enum

1. Initializing the enum member is not allow,
   

   enum Rules
   {
       a, b, c = d, d, e, f
   };
   public static void Main()
   {
       Rules i; // declare an enum variable
       for (i = Rules.a; i < Rules.f; i++) Console.WriteLine(" {0}", i + " has value of: " + (int) i);
       Console.WriteLine();
       Console.ReadKey();
   }

   c = d is not allow
   
   
2. Another variable declaration with same name is allow, but can’t create using new keyword.
   

   enum Rules
   {
       a, b, c, d, e, f
   };
   public static void Main()
   {
       int d = 2500; // another variable declared
       // new int e = 100; // error - A new expression requires
       Rules i; // declare an enum variable
       for (i = Rules.a; i < Rules.f; i++)
       {
           Console.WriteLine(" {0}", i + " has value of: " + (int) i);
           Console.WriteLine();
       }
       Console.WriteLine(" variable d has value of: " + d);
       Console.ReadKey();
   }

   new int e = 100; will get an error - A new expression requires
   
   
   
   
3. Value of enum can’t increment directly,
   

   enum Rules
   {
       a, b, c, d, e, f
   };
   public static void Main()
   {
       a++; // error - can not change the value of constant
       Rules i; // declare an enum variable
       for (i = Rules.a; i < Rules.f; i++)
       {
           Console.WriteLine(" {0}", i + " has value of: " + (int) i);
           Console.WriteLine();
       }
       Console.ReadKey();
   }

   a++; will get an error – can’t change the value of constant
   
   
4. Use of enum for initialization of another variable,
   

   enum Rules
   {
       a, b, c, d, e, f
   };
   public static void Main()
   {
       int z = Convert.ToInt16(Rules.b); //// use enum for use initialization of another variable
       Rules i; // declare an enum variable
       for (i = Rules.a; i < Rules.f; i++)
       {
           Console.WriteLine(" {0}", i + " has value of: " + (int) i);
           Console.WriteLine();
       }
       Console.WriteLine(" variable d has value of: " + z);
       Console.ReadKey();
   }

   
   
   
5. Size of enum can be decide at the time time of declaration enum,
   

   enum Rules
   {
       a, b, c, d, e, f
   };
   enum short_values: short
   {
       B1 = 01, B2 = 02
   }
   enum long_values: long
   {
       A1 = 123456789985, A2 = 45678954123
   }
   public static void Main()
   {
       Rules i; // declare an enum variable
       Console.WriteLine(" size of enum Rules has value of : {0} ", sizeof(Rules));
       Console.WriteLine(" size of enum short_values has value of : {0} ", sizeof(short_values));
       Console.WriteLine(" size of enum long_values has value of : {0} ", sizeof(long_values));
       Console.ReadKey();
   }

Summary

This blog will help fresher candidates to understand enum in depth.