C++计算程序运行时间

高精度计算运行时间，单位为s（浮点型）

#include <windows.h>  #include <stdio.h>  int main(int argc, char **argv)  {      LARGE_INTEGER freq;      LARGE_INTEGER start_t, stop_t;      double exe_time;      QueryPerformanceFrequency(&freq);      fprintf(stdout, "The frequency of your pc is %d.\n", freq.QuadPart);      QueryPerformanceCounter(&start_t);      Sleep(1000);      QueryPerformanceCounter(&stop_t);      exe_time = 1e3*(stop_t.QuadPart-start_t.QuadPart)/freq.QuadPart;      fprintf(stdout, "Your program executed time is %fms.\n", exe_time);       getchar();      return 0;  }