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 = ;
     double aLat = -80.11111111111;
     double aLong = -170.111111111111;
     struct timespec tpstart;
     struct timespec tpend;
     long timedif;
     clock_gettime(CLOCK_MONOTONIC, &tpstart);
     int i = ;
     for(i = ; i < ; i++)
     {
         encodeGeohash(aLat, aLong, );
         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)/;
     std::cout << "i = " << i << "\t timedif = " << timedif << std::endl;

     return ;
 }