p7-4.c

UNIX程序设计教程

#include <sys/time.h>
unsigned int
alarm(unsigned int seconds)
{
    struct itimerval old, new;
    new.it_interval.tv_usec = 0;
    new.it_interval.tv_sec = 0;
    new.it_value.tv_usec = 0;
    new.it_value.tv_sec = (long int) seconds;
    if (setitimer (ITIMER_REAL, &new, &old) < 0)
        return 0;
    else
        return old.it_value.tv_sec;
}