Function            isleapyear - is a year a leap year

  Syntax              boolean isleapyear(int checkyear);

  Prototype in        datehk.h       (isleapyear)

  Remarks             checks if checkyear is a leap year (29 days in
                      February.)

  Return value        returns TRUE if checkyear is a leap year, FALSE
                      otherwise.

  See also            valid_date()

  Example             #include <datehk.h>

                      main()
                      {
                           int year;

                      /* assign some value to year */
                           printf("year %d is ",year);
                           if (! isleapyear(year))
                                printf("not ");
                           printf("a leap year\n");
                      }