Enumerated Types

• An enumerated type is a type whose values are defined by a list of constants of type int.
  
  
• When defining an enumerated type, you can use any int values and can have any number of constants defined.
  
  For example, the following enumerated type defines a constant for the length of each month:
  
     enum MonthLength { JAN_LENGTH = 31, FEB_LENGTH = 28, MAR_LENGTH = 31,
        APR_LENGTH = 30, MAY_LENGTH = 31, JUN_LENGTH = 30, JUL_LENGTH = 31,
        AUG_LENGTH = 31, SEP_LENGTH = 30, OCT_LENGTH = 31, NOV_LENGTH = 30,
        DEC_LENGTH = 31};
  
  Note:Two or more named constants can receive the same int value.
  
  As a general rule of style, the names of enumerated values are all uppercase because they are symbolic constants.
  
  
• The default for the first enumeration constant is 0. The rest increase by 1 unless you set one or more of the enumeration constants.
  
  Therefore the type definition
  
     enum Direction { NORTH = 0, SOUTH = 1, EAST = 2, WEST = 3 };
  
  is equivalent to
  
     enum Direction { NORTH, SOUTH, EAST, WEST };
  
  In the type definition:
  
     enum MyEnum {ONE = 17, TWO, THREE, FOUR = -3, FIVE };
  
  ONE takes the value 17, TWO takes the next int value 18, THREE takes the next value 19 FOUR takes -3, and FIVE takes the next value, -2 .
  
  The above MonthLength enumerated type can also be defined as:
  
     enum MonthLength { JAN_LENGTH = 31, FEB_LENGTH = 28, MAR_LENGTH = 31,
        APR_LENGTH = 30, MAY_LENGTH, JUN_LENGTH = 30, JUL_LENGTH,
        AUG_LENGTH = 31, SEP_LENGTH = 30, OCT_LENGTH, NOV_LENGTH = 30,
        DEC_LENGTH};
  
  
• Some other examples are:
  
     enum dayType { SUN, MON, TUE, WED, THU, FRI, SAT };
     enum suitType { CLUBS, DIAMONDS, HEARTS, SPADES };
     enum FaceCardValues { JACK = 11, QUEEN, KING, ACE};
  
  
• There is a serious drawback in the use of enumerated types. The values of an enumerated type variable can only be input and output as the integers that they represent. Thus the statements:
  
     dayType day;
     day = WED;
     cout << day;
  
  produce the output 3, not WED.
  
  And in response to the statements
  
     cout << "Enter the day: ";
     cin >> day;
  
  the user must type an integer from 0 to 6, inclusive, not one of the symbolic names MON, TUE, etc.
  
  If you must output the symbolic name of an enumerated type value, you must translate the value into a string. A string-values function such as the following is most useful for this purpose.
  
  string Day2String(dayType day)
  {
     switch (day)
     {
        cast MON: return "Monday";
        cast TUE: return "Tuesday";
        cast WED: return "Wednesday";
        cast THU: return "Thursday";
        cast FRI: return "Friday";
        cast SAT: return "Saturday";
        cast SUN: return "Sunday";
     }
  }
  
  Now, the fragment
  
     dayType day;
     day = WED;
     cout << Day2String(day);
  
  would produce the output Wednesday.