Enumerated types work when you know in advance a finite (usually short) list of values that a data type can take on.  It is another user defined type which provides a way for attaching names to numbers, thereby increasing comprehensibility of the code.  The enum keyword automatically enumerates a list of words by assigning them values 0,1,2,3,4, and so on.

The general form of enum is:

enum variable name { list of constants separated by commas }; 
where enum is a keyword
variable name is the user defined variable name
list indicates the fixed constant values 
eg., 
enum days_of_week {sun, mon, tue, wed, thu, fri, sat};
Once we have specified the days of the week as shown we can define variable of this type.  
 
Example:
# include<iostream.h>
enum days_of_week {sun, mon, tue, wed, thu, fri, sat };
void main( )
{
 days_of_week day1, day2,day3;
 day1 = mon;
 day 2 = fri;
 int diff = day2 - day1;
 cout<<"days between = "<<diff<<endl;
 if (day1<day2)
  cout<< "day1 comes before day2\n";
} 
the values listed inside braces of enum keyword are called members. Enumerated means that all the values are listed.