C程序校验日期

C程序校验日期

#define is_leap_year(year) \
    ((((year) % 400 == 0) || ((year) % 4 == 0 && (year) % 100 != 0)) ? 1 : 0)


/**
 * time_is_valid()
 * 
 * test time is valid.
 * 
 * remark:
 * 
 *  The number of seconds(sec) after the minute, normally in the range 0 to 59,
 *   but can be up to 60 to allow for leap.
 *  Deciding when to introduce a leap second is the responsibility of the
 *   international earth rotation and reference systems service.
 * 
 * returns:
 *   0: error
 *   1: ok
 */
static int time_is_valid (int year, int mon, int day, int hour, int min, int sec)
{
    if (year < 1900 || year > 9999 || mon <= 0 || mon > 12 || day <= 0 || day > 31 || hour < 0 || hour > 24 || min < 0 || min > 59 || sec < 0 || sec > 60) {
        return 0;
    }

    if (mon == 1 || mon == 3 || mon == 5 || mon == 7 || mon == 8 || mon == 10 || mon == 12) {
        // 31 days ok
        return 1;
    } else if (mon == 4 || mon == 6 || mon == 9 || mon == 11) {
        if (day < 31) {
            return 1;
        }
    } else {
        // mon=2
        return (day > 29? 0 : (day < 29? 1: (is_leap_year(year)? 1 : 0)));
    }
    return 0;
}