_ AVGSECSPERYEAR DAYSPERLYEAR DAYSPERNYEAR DAYSPERWEEK ENOTSUP EOVERFLOW EPOCH_WDAY EPOCH_YEAR GRANDPARENTED HOURSPERDAY INITIALIZE INT_STRLEN_MAXIMUM is_digit isleap isleap_sum MAXVAL MINSPERHOUR MINVAL MONSPERYEAR SECSPERDAY SECSPERHOUR SECSPERMIN SECSPERREPEAT SECSPERREPEAT_BITS strtoimax TIME_T_MAX TIME_T_MIN TM_APRIL TM_AUGUST TM_DECEMBER TM_FEBRUARY TM_FRIDAY TM_JANUARY TM_JULY TM_JUNE TM_MARCH TM_MAY TM_MONDAY TM_NOVEMBER TM_OCTOBER TM_SATURDAY TM_SEPTEMBER TM_SUNDAY TM_THURSDAY TM_TUESDAY TM_WEDNESDAY TM_YEAR_BASE TWOS_COMPLEMENT TYPE_BIT TYPE_SIGNED YEARSPERREPEAT

isleap #define isleap (   y )    (((y) % 4) == 0 && (((y) % 100) != 0 || ((y) % 400) == 0))