C++ 计算时间差的五种方法小结-C/C++开发

本文主要介绍了C++ 计算时间差的五种方法小结，文中通过示例代码介绍的非常详细，对大家的学习或者工作具有一定的参考学习价值，需要的朋友们下面随着小编来一起学习学习吧

Qt计算时间的两种方法：

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

C++计算时间的五种方法：

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, 但是这个库Windows或Qt或VS2015都没有自带

const unsigned long SLEEP_TIME_MILL = 1000;

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

/**
 * QTime的精度为ms级
 */
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的精度为ms级
 */
void calcByClock() {
    clock_t startTime = clock();
    Sleep(SLEEP_TIME_MILL);
    clock_t endTime = clock();
    clock_t elapsed = endTime - startTime;
    qDebug()<<"clock ="<<elapsed<<"ms";
}

/**
 * GetTickCount的精度为ms级
 */
void calcByTickCount() {
    //返回自开机以来经历的毫秒数
    DWORD startTime = GetTickCount();
    Sleep(SLEEP_TIME_MILL);
    DWORD stopTime = GetTickCount();
    DWORD elapsed = stopTime - startTime;
    qDebug()<<"GetTickCount = "<<elapsed<<"ms";
}

///**
// * timeGetTime的精度为ms级
// * 必须添加Winmm.lib, 否则编译报错undefined reference
// */
//void calcByTimeGetTime() {
//    //返回自开机以来经历的毫秒数
//    DWORD startTime = timeGetTime();
//    Sleep(SLEEP_TIME_MILL);
//    DWORD stopTime = timeGetTime();
//    DWORD elapsed = stopTime - startTime;
//    qDebug()<<"timeGetTime = "<<elapsed<<"ms";
/

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