getitimer函数

 1 #include<stdio.h>
 2 #include<time.h>
 3 #include<sys/time.h>
 4 #include<unistd.h>
 5 #include<stdio.h>
 6 #include<time.h>
 7 #include<sys/time.h>
 8 #include<unistd.h>
 9 #include<signal.h>
10 #include<stdlib.h>
11 static void ElsfTimer(int signo )
12 {
13         struct timeval tp;
14         struct tm *tm;
15         gettimeofday(&tp,NULL);
16         tm=localtime(&tp.tv_sec);
17         printf("Sec=%ld\t",tp.tv_sec);
18         printf("Usec=%ld\t",tp.tv_usec);
19         printf("%d-%d-%d %d:%d:%d\n",tm->tm_year+1900,tm->tm_mon+1,tm->tm_mday,tm->tm_hour,tm->tm_min,tm->tm_sec);
20 }
21
22
23 static void InitTime(int tv_sec,int tv_usec)
24 {
25         struct itimerval value;
26
27         signal(SIGALRM,ElsfTimer);//注册SIGALRM函数
28         value.it_value.tv_sec=tv_sec;
29         value.it_value.tv_usec=tv_usec;
30         value.it_interval.tv_sec=tv_sec;
31         value.it_interval.tv_usec=tv_usec;
32         setitimer(ITIMER_REAL,&value,NULL);
33 }
34
35 int main()
36 {37         InitTime(5,0);   //设置setitimer的参数
38         struct itimerval ip;
39         getitimer(ITIMER_REAL,&ip);//获取计时器的设置
40         printf("%ld,%ld\n",ip.it_value.tv_sec,ip.it_value.tv_usec);//打印计时器的设置
41         while(1)
42         {
43                 printf("Sleeping ++\n");
44                 sleep(1);
45         }
46         exit(0);
47 }

程序运行结果如下：

 1 4,999996     //gettitimer获取到的计时器配置        与实际值5s还是有偏差的，说明函数处理计时也不是完全标准！
 2 Sleeping ++
 3 Sleeping ++
 4 Sleeping ++
 5 Sleeping ++
 6 Sleeping ++
 7 Sec=1454660611    Usec=533770    2016-2-5 16:23:31
 8 Sleeping ++
 9 Sleeping ++
10 Sleeping ++
11 Sleeping ++
12 Sleeping ++
13 Sec=1454660616    Usec=534003    2016-2-5 16:23:36
14 Sleeping ++
15 Sleeping ++
16 Sleeping ++
17 Sleeping ++
18 Sleeping ++
19 Sec=1454660621    Usec=533200    2016-2-5 16:23:41
20 Sleeping ++
21 Sleeping ++
22 ^C

可以看到每5s中断函数执行一次