（二）linux的计时函数

/*
 * util_time.h
 *
 *  Created on: 2018-6-4
 *      Author: 
 */

#ifndef UTIL_TIME_H_
#define UTIL_TIME_H_

#include <sys/time.h>

/* Return the UNIX time in microseconds */
long long ustime(void) {
    struct timeval tv;
    long long ust;

    gettimeofday(&tv, NULL);
    ust = ((long long)tv.tv_sec)*1000000;
    ust += tv.tv_usec;
    return ust;
}

/* Return the UNIX time in milliseconds */
long long mstime(void) {
    return ustime()/1000;
}

// #define UTIL_TIME_TEST
#ifdef UTIL_TIME_TEST
#include <unistd.h>
#include <iostream>

int main()
{
    long long llStart = mstime();
    sleep(2);
    long long llEnd=mstime();
    std::cout<<llEnd-llStart<<"ms"<<std::endl;

    return 0;
}
#endif

#endif /* UTIL_TIME_H_ */