C++?計(jì)算時(shí)間差的五種方法小結(jié)

更新時(shí)間：2023年04月25日 10:31:34 作者：福州司馬懿

本文主要介紹了C++?計(jì)算時(shí)間差的五種方法小結(jié)，文中通過示例代碼介紹的非常詳細(xì)，對(duì)大家的學(xué)習(xí)或者工作具有一定的參考學(xué)習(xí)價(jià)值，需要的朋友們下面隨著小編來一起學(xué)習(xí)學(xué)習(xí)吧

Qt計(jì)算時(shí)間的兩種方法：

QTime elapsed() : ms
QTime currentTime() : ms

C++計(jì)算時(shí)間的五種方法：

clock() : ms
GetTickCount() : ms
gettimeofday(time_val*, NULL) : us
QueryPerformanceFrequency(LARGE_INTEGER*) & QueryPerformanceCounter(LARGE_INTEGER*) : us
time(NULL) : s

#include <QThread>
#include <QTime>
#include <sys/time.h> ? //clock, gettimeofday, time
#include <windows.h> ? ?//Sleep, GetTickCount, timeGetTime, QueryPerformanceCounter
#include <QDebug>

//#pragma comment(lib, "winmm.lib") //timeGetTime, 但是這個(gè)庫Windows或Qt或VS2015都沒有自帶

const unsigned long SLEEP_TIME_MILL = 1000;

/**
?* QTime的精度為ms級(jí)
?*/
void calcByQtimeElapsed() {
? ? QTime time;
? ? time.start();
? ? QThread::msleep(SLEEP_TIME_MILL);
? ? int timeElapsed = time.elapsed();
? ? qDebug()<<"QTime.start & QTime.elspsed ="<<timeElapsed<<"ms";
}

/**
?* QTime的精度為ms級(jí)
?*/
void calcByQtimeCurrentTime() {
? ? QTime startTime = QTime::currentTime();
? ? QThread::msleep(SLEEP_TIME_MILL);
? ? QTime stopTime = QTime::currentTime();
? ? int elapsed = startTime.msecsTo(stopTime);
? ? qDebug()<<"QTime.currentTime ="<<elapsed<<"ms";
}

/**
?* clock的精度為ms級(jí)
?*/
void calcByClock() {
? ? clock_t startTime = clock();
? ? Sleep(SLEEP_TIME_MILL);
? ? clock_t endTime = clock();
? ? clock_t elapsed = endTime - startTime;
? ? qDebug()<<"clock ="<<elapsed<<"ms";
}

/**
?* GetTickCount的精度為ms級(jí)
?*/
void calcByTickCount() {
? ? //返回自開機(jī)以來經(jīng)歷的毫秒數(shù)
? ? DWORD startTime = GetTickCount();
? ? Sleep(SLEEP_TIME_MILL);
? ? DWORD stopTime = GetTickCount();
? ? DWORD elapsed = stopTime - startTime;
? ? qDebug()<<"GetTickCount = "<<elapsed<<"ms";
}

///**
// * timeGetTime的精度為ms級(jí)
// * 必須添加Winmm.lib, 否則編譯報(bào)錯(cuò)undefined reference
// */
//void calcByTimeGetTime() {
// ? ?//返回自開機(jī)以來經(jīng)歷的毫秒數(shù)
// ? ?DWORD startTime = timeGetTime();
// ? ?Sleep(SLEEP_TIME_MILL);
// ? ?DWORD stopTime = timeGetTime();
// ? ?DWORD elapsed = stopTime - startTime;
// ? ?qDebug()<<"timeGetTime = "<<elapsed<<"ms";
//}

/**
?* gettimeofday的精度為us級(jí)
?*/
void calcByGetTimeOfDay() {
? ? struct timeval startTime, stopTime;
? ? gettimeofday(&startTime, NULL);
? ? Sleep(SLEEP_TIME_MILL);
? ? gettimeofday(&stopTime, NULL);
? ? long elapsed = (stopTime.tv_sec-startTime.tv_sec) * 1000000 + (stopTime.tv_usec - startTime.tv_usec);
? ? qDebug()<<"gettimeofday ="<<elapsed<<"us";
}

/**
?* QueryPerformanceCounter的精度為us級(jí)
?*/
void calcByQueryPerformanceCounter() {
? ? LARGE_INTEGER frequency, startCount, stopCount;
? ? WINBOOL ret;
? ? //返回性能計(jì)數(shù)器每秒滴答的個(gè)數(shù)
? ? ret = QueryPerformanceFrequency(&frequency);
? ? if(ret) {
? ? ? ? ret = QueryPerformanceCounter(&startCount);
? ? }
? ? Sleep(SLEEP_TIME_MILL);
? ? if(ret) {
? ? ? ? QueryPerformanceCounter(&stopCount);
? ? }
? ? if(ret) {
? ? ? ? LONGLONG elapsed = (stopCount.QuadPart - startCount.QuadPart) * 1000000 / frequency.QuadPart;
? ? ? ? qDebug()<<"QueryPerformanceFrequency & QueryPerformanceCounter ="<<elapsed<<"us";
? ? }
}

/**
?* time(NULL)精確度為s級(jí)
?*/
void calcByTime() {
? ? time_t startTime = time(NULL);
? ? Sleep(SLEEP_TIME_MILL);
? ? time_t stopTime = time(NULL);
? ? long elapsed = stopTime - startTime;
? ? qDebug()<<"time(NULL) ="<<elapsed<<"s";
}

int main(int argc, char *argv[])
{
? ? calcByQtimeElapsed();
? ? calcByQtimeCurrentTime();
? ? calcByClock();
? ? calcByTickCount();
// ? ?calcByTimeGetTime();
? ? calcByGetTimeOfDay();
? ? calcByQueryPerformanceCounter();
? ? calcByTime();
? ? system("pause");
? ? return 0;
}