C ++ exact time using various time statistics cited

The method of obtaining time

1. ctime library

   Second only to statistics
   for algorithm problem: After you let the program run 1000 times the average at the time, a few times or more

   For project code: 1000 times? come on!
   We need to improve accuracy

2. time library

3. windows.h: millisecond
   std :: GetTickCount ()

4. windows.h: subtle level

LARGE_INTEGER tmp;
QueryPerformanceFrequency(&tmp);//QueryPerformanceFrequency()作用：返回硬件支持的高精度计数器的频率。

6. Linux platform: sys / time.h: milliseconds

   struct timeval time ;