QT-QVariant

struct student
{
    int iNo;
    QString strname;
    int age;
};
Q_DECLARE_METATYPE(student)

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include<QVariant>
#include<QDebug>
#include<QColor>

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);

    QVariant qv1(259);
    qDebug()<<"qv1:" << qv1.toInt();

    QVariant qv2("Hello");
    qDebug()<<"qv2: " << qv2.toString();

    QMap<QString, QVariant> qmap;
    qmap["int"] = 2025;
    qmap["double"] = 3.14;
    qmap["string"] = "world";
    qmap["color"] = QColor(255,255,0);
    qDebug()<<qmap;
    qDebug()<<qmap["int"] << qmap["int"].toInt();
    qDebug()<<qmap["double"] << qmap["double"].toDouble();
    qDebug()<<qmap["string"] << qmap["string"].toString();
    qDebug()<<qmap["color"] << qmap["color"].value<QColor>();

    QVariant qv3;
    //类似于var  在初次赋值的时候决定类型
    qv3 = 17.9;
    qDebug()<<qv3;


    QStringList qsl;
    qsl << "A" <<"b"<<"C" <<"d" <<"e" <<"F";
    QVariant qvsl(qsl);
    if(qvsl.type() == QVariant::StringList)
    {
        QStringList qlist = qvsl.toStringList();
        for(int i = 0 ; i < qlist.size(); i++)
            qDebug()<< qlist.at(i);
    }

    //应用自定义类型和QVariant配合使用
    student stu;
    stu.age = 18;
    stu.iNo =1;
    stu.strname = "zhangsan";

    QVariant qstu = QVariant::fromValue(stu); //使用静态方法保存数据
    if(qstu.canConvert<student>())
    {
        student t_stu = qstu.value<student>();  //获取数据
        student t_stu2 = qvariant_cast<student>(qstu); //类型转换
        qDebug()<<"student :{ ino = " << t_stu.iNo
               << "name = " << t_stu.strname
                << "age = " << t_stu.age;
     }
}


MainWindow::~MainWindow()
{
    delete ui;
}