Linux c++ time different

下面这个函数可以得到微秒级别：

#include<time.h>

int clock_gettime(clockid_t clk_id,struct timespec *tp);

函数"clock_gettime"是基于Linux C语言的时间函数,他可以用于计算精度和纳秒

具体的可以参考 clock_gettime 函数

 

#include <iostream>　　
#include <cstdlib>
#include <cstdio>
#include <sys/time.h>
#include <time.h>
#include <string>

using namespace std;

string encodeGeohash(const double & theLat, const double & theLong, int thePrecision);

int main(int argc, char **argv)
{
    const int MILLION = 1000000;
    double aLat = -80.11111111111;
    double aLong = -170.111111111111;
    struct timespec tpstart;
    struct timespec tpend;
    long timedif;
    clock_gettime(CLOCK_MONOTONIC, &tpstart);
    int i = 0;
    for(i = 0; i < 480000000; i++)
    {
        encodeGeohash(aLat, aLong, 40);
        aLat += 0.000001;
        aLong += 0.000001;
    }

    clock_gettime(CLOCK_MONOTONIC, &tpend);
    timedif = MILLION*(tpend.tv_sec-tpstart.tv_sec)+(tpend.tv_nsec-tpstart.tv_nsec)/1000;
    std::cout << "i = " << i << "	 timedif = " << timedif << std::endl;

    return 0;
}