setitimer定时器

#include <sys/select.h>
#include <sys/time.h>
#include <stdio.h>
#include <unistd.h>
#include <signal.h>

int n = 0;
struct itimerval value;
void timefunc(int sig)
{
    fprintf(stderr, "timer[%d]\n", n++);
    if (n > 5)
    {
        getitimer(ITIMER_REAL, &value);
        value.it_value.tv_sec = 0;
        value.it_value.tv_usec = 0;
        value.it_interval.tv_sec = 0;
        value.it_interval.tv_usec = 0;
        setitimer(ITIMER_REAL, &value, NULL);
        fprintf(stderr, "time over.\n");
    }
}

void main()
{
    value.it_value.tv_sec = 2;
    value.it_value.tv_usec = 500000;
    value.it_interval.tv_sec = 1;
    value.it_interval.tv_usec = 500000;

    signal(SIGALRM, timefunc);
    setitimer(ITIMER_REAL, &value, NULL);
    while(1)
    {
        fprintf(stderr, ".");
        sleep(1);
    };
}