怎样计算程序运行时间

[kaishuinanhai]

函数应该怎样写呢，运行程序所花费的时间为准进行对比

[野男孩]

DWORD ticks = GetTickCount();

Function();

ticks = GetTickCount() - ticks;

cout << "Function() cost " << ticks << "ms";

[ryfdizuo]

clock_t begin = clock();
function();
clock() - begin; // 为时间差,单位ms

[kael_9527]

LARGE_INTEGER swStart,swStop;
Stopwatch(0,&swStart,&swStop);
运行代码
otime=Stopwatch(1,&swStart,&swStop);
totaltime+=otime;
tmp.Format("%.1f",otime*1000);
函数代码
float CRegDemoDlg::Stopwatch(int start0stop1,LARGE_INTEGER *pstart,LARGE_INTEGER *pstop)
{
static LARGE_INTEGER m_swFreq;
static float elapsedtime=0.0;
static int flag=0;
if(!flag){
QueryPerformanceFrequency(&m_swFreq);
flag=1;
}
if (start0stop1==0) QueryPerformanceCounter(pstart);
else {
QueryPerformanceCounter(pstop);
if (m_swFreq.LowPart==0 && m_swFreq.HighPart==0) elapsedtime = -1;
else {
elapsedtime = (float)(pstop->LowPart - pstart->LowPart);
if (elapsedtime < 0) elapsedtime += 2^32;
elapsedtime /= (m_swFreq.LowPart+m_swFreq.HighPart * 2^32);
}
return elapsedtime;
}
return 0;
}
精度比较高的，希望合用

[Defonds]

调用的时间差

[luciferisnotsatan]

    FILETIME ct;
    FILETIME et;
    FILETIME kt;
	FILETIME ut;
    __int64 ktStart=0;
    __int64 utStart=0;
    __int64 ktStop=0;
	__int64 utStop=0;
    LARGE_INTEGER ss,ee,fq;
    HANDLE cur;

	int i,j,dump;

	cur = GetCurrentThread();

    QueryPerformanceCounter(&ss);  //QueryPerformanceCounter的单位应该是cpu的时间周期时间，1/cpu频率
	GetThreadTimes(cur,&ct,&et,&kt,&ut);  // 起始时的内核时间和用户时间。不过精度也就10ms级
    ktStart = (((__int64)kt.dwHighDateTime)<<32) + (__int64)kt.dwLowDateTime;
	utStart = (((__int64)ut.dwHighDateTime)<<32) + (__int64)ut.dwLowDateTime;
    
    // put your code here, such as:
	Sleep(10000);  //sleep消耗的不是程序所用的时间。scanf函数等待的时间等也一样不是程序消耗的时间
	for(i=0;i<10000;i++)
	{		
		dump = 0;
        for(j=0;j<10000;j++)
		{
			dump += j*j;
		}
	}
	// finish

	GetThreadTimes(cur,&ct,&et,&kt,&ut);  // 结束时的内核时间和用户时间
    ktStop = (((__int64)kt.dwHighDateTime)<<32) + (__int64)kt.dwLowDateTime;
	utStop = (((__int64)ut.dwHighDateTime)<<32) + (__int64)ut.dwLowDateTime;

	printf("Kernel Time: %llu ms\n", (ktStop - ktStart)/10000);  //FILETIME的单位是100ns，除10000变ms
	printf("User Time: %llu ms\n", (utStop - utStart)/10000);
    QueryPerformanceCounter(&ee);
	QueryPerformanceFrequency(&fq);
    // QueryPerformanceCounter高精度的，但记得并不是代码实际消耗的时间。会把sleep的那10秒也计入。
	printf("Time: %llu us\n", (ee.QuadPart-ss.QuadPart)/(fq.QuadPart/1000000)); 

[luciferisnotsatan]

下面这段代码可以用来或者程序运行的时间。
建个控制台程序，把代码考进去。加上头文件
#include <stdio.h>
#include <windows.h>

STARTUPINFO si;
    PROCESS_INFORMATION pi;
    FILETIME ct;
    FILETIME et;
    FILETIME kt;
	FILETIME ut;
    __int64 tm=0;    
    SYSTEMTIME st;


	if(2 > argc)
		return 1;

    ZeroMemory( &si, sizeof(si) );
    si.cb = sizeof(si);
    ZeroMemory( &pi, sizeof(pi) );

    // Start the child process. 
    if( !CreateProcess( NULL,   // No module name (use command line). 
        argv[1], // Command line. 命令行的参数
        NULL,             // Process handle not inheritable. 
        NULL,             // Thread handle not inheritable. 
        FALSE,            // Set handle inheritance to FALSE. 
        0,                // No creation flags. 
        NULL,             // Use parent's environment block. 
        NULL,             // Use parent's starting directory. 
        &si,              // Pointer to STARTUPINFO structure.
        &pi )             // Pointer to PROCESS_INFORMATION structure.
    ) 
    {
        printf( "CreateProcess failed (%d).\n", GetLastError() );
        return 1;
    }

    // Wait until child process exits.
    WaitForSingleObject( pi.hProcess, INFINITE );
	


 
	GetProcessTimes(pi.hProcess,&ct,&et,&kt,&ut);


    FileTimeToSystemTime(&ct,&st);
	printf("Creation Time: %04d-%02d-%02d %02d:%02d:%02d.%03d\n", st.wYear, st.wMonth, st.wDay, st.wHour, st.wMinute, st.wSecond, st.wMilliseconds);
    FileTimeToSystemTime(&et,&st);    
	printf("Exit Time: %04d-%02d-%02d %02d:%02d:%02d.%03d\n", st.wYear, st.wMonth, st.wDay, st.wHour, st.wMinute, st.wSecond, st.wMilliseconds);
	tm = (((__int64)kt.dwHighDateTime)<<32) + (__int64)kt.dwLowDateTime;
	printf("Kernel Time : %llu ms\n", tm/10000);
    tm = (((__int64)ut.dwHighDateTime)<<32) + (__int64)ut.dwLowDateTime;
	printf("User Time : %llu ms\n",tm/10000);

    // Close process and thread handles. 
    CloseHandle( pi.hProcess );
    CloseHandle( pi.hThread );

在命令行输入：该程序.exe notepad.exe

notepad.exe退出后会输出相关时间

[matrixcl]

这个看具体要求了

一般函数 执行前 GetTickCount，执行后GetTickCount，数值相减。这个时间精度是以15.625秒单位的，误差较大。timeGetTime更精确一点，精确到毫秒。

如果函数执行时间未达到毫秒级，可以循环多次计算平均耗时。
另外还有QueryPerformanceCounter、QueryPerformanceFrequency，理论上可以取到cpu时钟级别的时间间隔，但考虑函数调用的开销，实际误差比这大多了。但仍然远比毫秒时间精确。