Qt5数据类型转换

1。头文件

#include <QCoreApplication>
#include <QDebug>
#include <QtMath>
#include <QDateTime>
#include <QTextCodec>
#include <iostream>

2。代码

void typeTrans()
{
    //1.QString 转 数字
    int numberA = 2;
    QString numberB = "5";
    qDebug() << "1)" << "2+5= " << numberA + numberB.toInt();
    //2.数字 转 QString
    float numberC = 10.25;
    float numberD = 2;
    QString result = QString::number(numberC * numberD);
    qDebug() << "2)" << "10.25+2= " << result;
    //3.round down
    float numberE = 10.3;
    float numberF = qFloor(numberE);
    qDebug() << "3)" << "Floor of 10.3 is " << numberF;
    //4.the smallest integral value not smaller than its initial value
    float numberG = 10.3;
    float numberH = qCeil(numberG);
    qDebug() << "4)" << "Ceil of 10.3 is " << numberH;
    //5.QString 转 QDateTime
    QString dateTimeAString = "2021-02-09 20:30:33";
    QDateTime dateTimeA = QDateTime::fromString(dateTimeAString, "yyyy-MM-dd hh::mm::ss");
    qDebug() << "5)" << dateTimeA;
    //6.QDateTime 转 QString
    QDateTime dateTimeB = QDateTime::currentDateTime();
    QString dateTimeBString = dateTimeB.toString("dd/MM/yy hh:mm");
    qDebug() << "6)" << dateTimeBString;
    //7.8.Upper and Lower
    QString hello1 = "Hello World!";
    qDebug() << "7)" << hello1.toUpper();
    qDebug() << "8)" << hello1.toLower();
    //9.QVariant
    QVariant aNumber = QVariant(3.14159);
    double aResult = 12.5*aNumber.toDouble();
    qDebug() << "9) 12.5*3.14159 = " << aResult;
    //10.
    qDebug() << "10)";
    QVariant myData = QVariant(10);
    qDebug() << myData;
    myData = myData.toFloat()/2.135;
    qDebug() << myData;
    myData = true;
    qDebug() << myData;
    myData = QDateTime::currentDateTime();
    qDebug() << myData;
    myData = "Good Bye!";
    qDebug() << myData;

}

3。运行结果：

其中，最要注意的是QVariant，这是一个非常强大的类型，可以定义组，类等Qt对象。

https://blog.csdn.net/xiaopei_yan/article/details/81410092

https://doc.qt.io/qt-5/qvariant.html

https://blog.csdn.net/woniulx2014/article/details/82752835

多谢，亲爱的美美。