#include <stdlib.h>

#include <signal.h>

static int count = ;

static struct itimerval oldtv;

struct itimerval itv;

void set_timer()

{

        itv.it_interval.tv_sec = ;

        itv.it_interval.tv_usec = ;  //启动后的定时器每隔990ms唤醒一次

        itv.it_value.tv_sec = ;

        itv.it_value.tv_usec = ;   //定时器在50ms后启动

        setitimer(ITIMER_REAL, &itv, &oldtv);

           //ITIMER_REAL表示每次定时器唤醒时将会触发SIGALRM信号

}

void shut_timer()

{

        itv.it_value.tv_sec = ;        //将启动参数设置为0,表示定时器不启动

        itv.it_value.tv_usec = ;

        setitimer(ITIMER_REAL, &itv, &oldtv);

}

void signal_handler(int m)

{

        count ++;

        printf("%d\n", count);

        if(count==)     //调用4次后,关闭定时器

          shut_timer();

}

int main()

{

        signal(SIGALRM, signal_handler);  //将SIGALRM信号与signal_handler函数建立关系,当信号触发时便会调用该函数.

        set_timer();

        while(count < );

        exit();

        return ;

}