Enumeration in C

Enumeration is a derived data type similar to a structure or a union Its members are constants that are written as identifiers, though they have signed integer values Enumeration constants are automatically assigned equivalent integer values. An enumeration is a user-defined data type consists of integral constants and each integral constant is give a name. Keyword enum is used to defined enumerated data type.

Its first member values start with 0 and are incremented by 1 also we can set values explicitly with using equal to operator (=).

Syntax of enumeration in C is given below.

enum type_name {

member1,

member 2,

… . ,

member n

};

Enumeration variables can be declared as given below.

storage-class-type  enumtype_name var1, var2 ;

Example of enumeration in C

enum days{

SUN,

MON,

TUE,

WED,

THU,

FRE,

SAT

};

Here enumeration constants are

SUN  0  MON 1 TUE 2 WED 3 THU 4 FRI 5 SAT 6

Also we can assign explicit values to enumeration constants like given below.

enum days{

SUN = 10,

MON = 11,

TUE = 12,

WED = 13,

THU = 14,

FRE = 15,

SAT = 16

};

In above example enumeration constants are

SUN  10  MON 11 TUE 12 WED 13 THU 14 FRI 15 SAT 16

See an example C program

#include <stdio.h>

enum days{ sunday, monday, tuesday, wednesday, thursday, friday, saturday};

int main()

{

enum days today;

today = wednesday;

printf(“%d day”,today);

return 0;

}

Output:
$  ./a.out

3