linux下setitimer定时器与定时器取消

#include <stdio.h>  
#include <signal.h>  
#include <time.h>  
#include <string.h>  
#include <stdlib.h>  
#include <unistd.h>  

void timer_thread(union sigval v)  
{
    static int i = 0;
    printf ("timer_thread function! %d\n", v.sival_int);
    printf ("i = %d\n", ++i);
}  

int main()  
{  
    timer_t timerid;  
    struct sigevent evp;  
    memset(&evp, 0, sizeof(struct sigevent));       //清零初始化  

    evp.sigev_value.sival_int = 111;                //也是标识定时器的，回调函数可以获得  
    evp.sigev_notify = SIGEV_THREAD;                //线程通知的方式，派驻新线程  
    evp.sigev_notify_function = timer_thread;       //线程函数地址  

    if (timer_create(CLOCK_REALTIME, &evp, &timerid) == -1)  
    {   
        perror("fail to timer_create");  
        exit(-1);  
    }   

    /* 第一次间隔it.it_value这么长,以后每次都是it.it_interval这么长,就是说it.it_value变0的时候会装载it.it_interval的值 */
    struct itimerspec it;  
    it.it_interval.tv_sec = 2;  
    it.it_interval.tv_nsec = 0;  
    it.it_value.tv_sec = 3;  
    it.it_value.tv_nsec = 0;  

    if (timer_settime(timerid, 0, &it, NULL) == -1)  
    {   
        perror("fail to timer_settime");
        exit(-1);
    }

    //pause();
    while (1);

    return 0;
}
/* 
 * int timer_gettime(timer_t timerid, struct itimerspec *curr_value); 
 * 获取timerid指定的定时器的值，填入curr_value 
 */

编译需加：-lrt

输出结果：

(倒计时3秒)

timer_thread function! 111
i = 1
(每2s)
timer_thread function! 111

i = 2
(每2s)
timer_thread function! 111
i = 3
(每2s)
timer_thread function! 111
i = 4



linux下取消用setitimer设置的定时器
setitimer设置it_interval和it_value为零： 

void uninit_time()  
{  
    struct itimerval value;  
    value.it_value.tv_sec = 0;  
    value.it_value.tv_usec = 0;  
    value.it_interval = value.it_value;  
    setitimer(ITIMER_REAL, &value, NULL);  
}