Enumeration in C#

Enum

An enumerated type is declared using the enum keyword.

By default, the enumerator values are 0,1,2 …etc  

For example, in the following enumeration, Sat  is 0, Sun is 1, Mon is 2, and so forth.

 

 

The approved types for an enum are byte, sbyte, short, ushort, int, uint, long, or ulong.

 

Enums have these benefits:

• Enum variable only allow permitted values that it can take and restrict the others. (i.e anything which is not a day cannot be added to the above example)
• They force a programmer to think about all the possible values that the enum can take.
• They increase readability of the source code.

You can use extension methods to add functionality specific to a particular enum type.

Copy and run this program in Windows Form Application

 

Days enumeration represents the possible days in a week.  An extension method named weekEnd is added to the Days type so that each instance of that type now "knows" whether the day is a week end or not.

 

using System.Linq;

using System.Threading.Tasks;

using System.Windows.Forms;

using System;

using System.Collections.Generic;

using System.Linq;

 

namespace EnumExtension

{

    // Define an extension method in a non-nested static class.

    public static class Extensions

    {

        public static Days weekendDay1 = Days.Sun;

        public static Days weekendDay2 = Days.Sat;

 

        public static bool weekEnd(this Days day)

        {

            if (day == weekendDay1 || day == weekendDay2)

                return true;

            else

                return false;

 

        }

    }

 

    public enum Days { Sat = 0, Sun = 1, Mon = 2, Tue = 3, Wed = 4, Thurs = 5, Fri = 6 };

    class EnumExtension

    {

        static void Main(string[] args)

        {

            Days day1 = Days.Mon;

            Days day2 = Days.Sun;

 

            Console.WriteLine("\r\nFinding if the day is a week end!\r\n");

            Console.WriteLine("Day1 {0} a week end.", day1.weekEnd() ? "is" : "is not");

            Console.WriteLine("Day2 {0} a week end.", day2.weekEnd() ? "is" : "is not");

        }

    }

}