clock_t times(struct tms *buf);
struct tms is as defined in /usr/include/sys/times.h:
struct tms {
time_t tms_utime; /* user time */
time_t tms_stime; /* system time */
time_t tms_cutime; /* user time of children */
time_t tms_cstime; /* system time of children */
};
times returns the number of clock ticks that have elapsed since the system has been up.