timeradd(3) Library Functions Manual timeradd(3) timeradd, timersub, timercmp, timerclear, timerisset - (libc -lc) #include void timeradd(struct timeval *a, struct timeval *b, struct timeval *res); void timersub(struct timeval *a, struct timeval *b, struct timeval *res); void timerclear(struct timeval *tvp); int timerisset(struct timeval *tvp); int timercmp(struct timeval *a, struct timeval *b, CMP); glibc ( feature_test_macros(7)): : glibc 2.19: _DEFAULT_SOURCE glibc 2.19 : _BSD_SOURCE timeval : struct timeval { time_t tv_sec; /* */ suseconds_t tv_usec; /* */ }; timeradd() a b timeval res. res->tv_usec 0 999,999. timersub() b a timeval res. res->tv_usec 0 999,999. timerclear() timeval tvp : 1970-01-01 00:00:00 +0000 (UTC). timerisset() ( ) timeval tvp . timercmp() a b CMP ( ) (0) . ( Linux/glibc) timercmp() CMP >= <= == !timercmp(..., <) !timercmp(..., >) !timercmp(..., !=) timerisset() timercmp() ( ) (0). . . BSD. gettimeofday(2), time(7) 3 . . : . 6.18 8 2026 timeradd(3)