Qt QDateTime计算时间差的实现示例

#include "MainWindow.h"

#include <QApplication>
#include <QTime>
#include <QDateTime>
#include <QDebug>

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    MainWindow w;
//    w.show();


//    int iCount[10000000] = {1};
    int *pAllocation = new int[10000000];
    int item = 0;
    QDateTime time1 = QDateTime::currentDateTime();
    QTime startTime = QTime::currentTime();
    for(quint64 i=0; i<9000000000; i++)
    {
        item = i;
    }

    QDateTime time2 = QDateTime::currentDateTime();
    int days = time1.daysTo(time2);
    qDebug() << "Cast days=" << days;

    quint64 sTime = time1.toTime_t();
    quint64 eTime = time2.toTime_t();

    quint64 costTime = eTime - sTime;
    qDebug() << "eTime - sTime=" << costTime;
    QDateTime elapseTime = QDateTime::fromTime_t(costTime);
    qDebug() << "Elapsed time=" << elapseTime;

    QTime endTime = QTime::currentTime();



    int elapsed = startTime.secsTo(endTime);
    qDebug() << startTime.secsTo(endTime);


//    int ndaysec = 24*60*60;
//    qDebug() << "Day = " << (etime - stime)/(ndaysec) + ((etime - stime)%(ndaysec)+(ndaysec-1))/(ndaysec) - 1;

    QDateTime dateTime;
    QString elapsedTime = dateTime.fromTime_t(elapsed).toString("yyyy-MM-dd hh:mm:ss[:zzz]");
    qDebug() << "Cast time=" << elapsedTime;

    return a.exec();
}

#include <iostream>
#define BOOST_DATE_TIME_POSIX_TIME_STD_CONFIG		// 必须在头文件之前定义宏，否则无效！！！
#include <boost/date_time/posix_time/posix_time.hpp>
 
int main(int argc, char **argv) {
	// 第四个参数，如果精确度是微秒，单位就是微秒，如果精确度是纳秒，单位就是纳秒
	boost::posix_time::time_duration td(1, 10, 30, 1000);				// 01:10:30
	// 查看当前的精确度
	if (td.resolution() == boost::date_time::nano) printf("精确度：纳秒\n");
	else printf("精确度：微秒\n");
	// 返回秒的小数部分的位数（微秒6位，纳秒9位）
	std::cout << td.num_fractional_digits() << std::endl;
 
	// 对于以下输出，默认微秒精度输出：01:10:30.001000  纳秒精度输出：01:10:30.000001000
	std::cout << td << std::endl;
	// 对于以下输出，在纳秒精度下，微秒会被忽略（微秒:4230001 纳秒:4230000）
	std::cout << td.total_milliseconds() << std::endl;
	// 下面的这个方法，就是输出小数点后面的数值，单位随精确度变化
	std::cout << td.fractional_seconds() << std::endl;
	return 0;
}

QString starttime ="2022-11-11 12:00:00";
QString endtime = "2022-11-13 12:00:01";
QDateTime start = QDateTime::fromString(starttime, "yyyy-MM-dd hh:mm:ss");
QDateTime end = QDateTime::fromString(endtime, "yyyy-MM-dd hh:mm:ss");
uint stime = start.toTime_t();
uint etime = end.toTime_t();

QDateTime time = QDateTime::fromTime_t(timeT);