Enumeration

Enumeration is a user defined datatype in C language. It is used to assign names to the integral constants which make a program easy to read and maintain.

The keyword “enum” is used to declare an enumeration.

The following is the way to define the enum in C:

enum  flag{integer_const1, integer_const2,.....integter_constN}; 

In the above declaration, enum named as flag containing 'N' integer constants is defined. The default value of integer_const1 is 0, integer_const2 is 1, and so on.

If we do not explicitly assign values to enum names, the compiler by default assigns values starting from 0. 

Example:

enum fruits{mango, apple, banana, papaya}; 

The default value of mango is 0, apple is 1, banana is 2, and papaya is 3.

To change these default values, then :

enum fruits{ mango=2, apple=1, banana=5, papaya=7}; 

Variables of type enum can also be defined. They can be defined in two ways:

enum  week{Mon, Tue, Wed};

enum  week  day;

// Or

enum  week{Mon, Tue, Wed}day;

An example program to demonstrate working of enum in C

#include<stdio.h>

 enum week{Mon, Tue, Wed, Thur, Fri, Sat, Sun};

 void main()

{

    enum  week   day;

    day = Wed;

    printf("%d",day);  

} 

Example 2:

#include <stdio.h>

enum day {sunday = 1, monday, tuesday = 5, wednesday, thursday = 10, friday, saturday};

 void main()

{

printf("%d %d %d %d %d %d %d", sunday, monday, tuesday,wednesday, thursday, friday, saturday);

}

Output:

1  2  5  6  10  11  12

Note: We can assign values to some name in any order. All unassigned names get value as value of previous name plus one.