题目

[TOC]

1. 采用libevent库，编写一个间隔几秒钟打印一遍程序的程序。

参考答案：

#include<event.h>
#include <stdio.h>

/*

编译命令 gcc 文件 -levent

*/

void func_cb(evutil_socket_t fd, short flag, void* div_arg)
{
    struct timeval* tv = div_arg;
    struct timeval cur_tv;
    evutil_gettimeofday(&cur_tv, NULL);
    evutil_timersub(&cur_tv, tv, &cur_tv);
    double elapsed = cur_tv.tv_sec * 1000 + cur_tv.tv_usec/1000;

    printf("hello world! ");
    printf("elapsed %f\n", elapsed);
}

int main(int argc ,char* argv)
{
    struct event ev;
    struct event_base* base;
    struct timeval tv;
    struct timeval interval;
    base = event_base_new();
    evutil_gettimeofday(&tv, NULL);

        //EV_PERSIST
    event_assign(&ev, base, -1, 0, func_cb, &tv);

    evutil_timerclear(&interval);
    interval.tv_sec = 1;
    event_add(&ev, &interval);

    event_base_dispatch(base);    
    return 0;
}