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";
//}
/**
* gettimeofday的精度为us级
*/
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的精度为us级
*/
void calcByQueryPerformanceCounter() {
LARGE_INTEGER frequency, startCount, stopCount;
WINBOOL ret;
//返回性能计数器每秒滴答的个数
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)精确度为s级
*/
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;
}
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