Enum in C# Programming

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

Output:



Some Rules for Enum

1. Initializing the enum member is not allow,
   
   1. enum Rules
   2. {
   3. a, b, c = d, d, e, f
   4. };
   5. public static void Main()
   6. {
   7. Rules i; // declare an enum variable
   8. for (i = Rules.a; i < Rules.f; i++) Console.WriteLine(" {0}", i + " has value of: " + (int) i);
   9. Console.WriteLine();
   10. Console.ReadKey();
   11. }
   c = d is not allow
   
   
2. Another variable declaration with same name is allow, but can’t create using new keyword.
   
   1. enum Rules
   2. {
   3. a, b, c, d, e, f
   4. };
   5. public static void Main()
   6. {
   7. int d = 2500; // another variable declared
   8. // new int e = 100; // error - A new expression requires
   9. Rules i; // declare an enum variable
   10. for (i = Rules.a; i < Rules.f; i++)
   11. {
   12. Console.WriteLine(" {0}", i + " has value of: " + (int) i);
   13. Console.WriteLine();
   14. }
   15. Console.WriteLine(" variable d has value of: " + d);
   16. Console.ReadKey();
   17. }
   new int e = 100; will get an error - A new expression requires
   
   
   
   
3. Value of enum can’t increment directly,
   
   1. enum Rules
   2. {
   3. a, b, c, d, e, f
   4. };
   5. public static void Main()
   6. {
   7. a++; // error - can not change the value of constant
   8. Rules i; // declare an enum variable
   9. for (i = Rules.a; i < Rules.f; i++)
   10. {
   11. Console.WriteLine(" {0}", i + " has value of: " + (int) i);
   12. Console.WriteLine();
   13. }
   14. Console.ReadKey();
   15. }
   a++; will get an error – can’t change the value of constant
   
   
4. Use of enum for initialization of another variable,
   
   1. enum Rules
   2. {
   3. a, b, c, d, e, f
   4. };
   5. public static void Main()
   6. {
   7. int z = Convert.ToInt16(Rules.b); //// use enum for use initialization of another variable
   8. Rules i; // declare an enum variable
   9. for (i = Rules.a; i < Rules.f; i++)
   10. {
   11. Console.WriteLine(" {0}", i + " has value of: " + (int) i);
   12. Console.WriteLine();
   13. }
   14. Console.WriteLine(" variable d has value of: " + z);
   15. Console.ReadKey();
   16. }
   
   
   
5. Size of enum can be decide at the time time of declaration enum,
   
   1. enum Rules
   2. {
   3. a, b, c, d, e, f
   4. };
   5. enum short_values: short
   6. {
   7. B1 = 01, B2 = 02
   8. }
   9. enum long_values: long
   10. {
   11. A1 = 123456789985, A2 = 45678954123
   12. }
   13. public static void Main()
   14. {
   15. Rules i; // declare an enum variable
   16. Console.WriteLine(" size of enum Rules has value of : {0} ", sizeof(Rules));
   17. Console.WriteLine(" size of enum short_values has value of : {0} ", sizeof(short_values));
   18. Console.WriteLine(" size of enum long_values has value of : {0} ", sizeof(long_values));
   19. Console.ReadKey();
   20. }
   

Summary

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