/******************************************************************************* isLeapYear(year: positive integer): boolean Check whether a given year is a leap year. Input year Year to check (> 1581). Returns TRUE when `year' is a leap year, FALSE if it is not. Description In the Gregorian calendar a year is a leap year when it is divisible by 4 and is not a turn of the century exept when the turn of the century is in a year being a multiple of 400. The Gregorian calendar was introduced by pope Gregorius XIII in 1582. Source: Winkler Prins Technische Encyclopedie. *******************************************************************************/ int isLeapYear(unsigned int year) { assert(year > 1581); return(((year % 4 == 0) && (year % 100)) || (year % 400 == 0)); } *************************************************************************** int islyr (int year) { return((year % 400 == 0) || ((year % 100) && (year % 4 == 0))) } /* islyr */ Rule 1: If the year is divisible by 400, it IS a leap year. Rule 2: If the year is divisible by 100, it IS NOT a leap year. Rule 3: If the year is divisible by 4, it IS a leap year.