Accurate timing in C/C ++

Timing A program is too important for programmers. The clock () on windows is not accurate enough, and the precision is only 10 ms, which is really sad. I have studied how to use C, C ++ timing functions in windows.
It mainly refers to the use of two functions. I first paste a piece of code that can be run and then talk about these two functions.
[Cpp]
1. # include <windows. h>
2. # include <stdio. h>
3. int main (int argc, char ** argv)
4 .{
5. LARGE_INTEGER freq;
6. LARGE_INTEGER start_t, stop_t;
7. double exe_time;
8. QueryPerformanceFrequency (& freq );
9. fprintf (stdout, "The frequency of your pc is % d. \ n", freq. QuadPart );
10. QueryPerformanceCounter (& start_t );
11. Sleep (1, 1000 );
12. QueryPerformanceCounter (& stop_t); www.2cto.com
13. exe_time = 1e3 * (stop_t.QuadPart-start_t.QuadPart)/freq. QuadPart;
14. fprintf (stdout, "Your program executed time is % fms. \ n", exe_time );
15. getchar ();
16. return 0;
17 .}

1. LARGE_INTEGER is actually a union in Microsoft's compiler. Its definition is as follows:
 
[Cpp]
1. typedef union _ LARGE_INTEGER
2 .{
3. struct
4 .{
5. DWORD LowPart;
6. LONG HighPart;
7 .};
8. struct
9 .{
10. DWORD LowPart;
11. LONG HighPart;
12.} u;
13. LONGLONG QuadPart;
14.} LARGE_INTEGER, * PLARGE_INTEGER;
If your compiler supports 64-bit integers, you can use QuadPart to reference the value of a variable. If your compiler does not support 64-bit integers, you can use LowPart and HighPart to reference the 64-bit integer's low 32-bit and high 32-bit.
2. QueryPerformanceFrequncy (LARGE_INTEGER * freq)
It is used to obtain how many times your machine executes in one second, that is, your clock cycle.
3. QueryPerformanceCounter (LARGE_INTEGER * lpPerformanceCount)
It obtains the number of clock cycles executed by the CPU since it is started.

Author: bendanban