Qt入门（常用类、方法、信息槽）

常用类

QApplication a(argc, argv); //实例化一个应用
QLabel label("Hello world"); //标签
QPushButton button("Quit"); //button
MainWindow b;b.show(); //窗口
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常用方法

QObject::connect()有五个重载
QMetaObject::Connection connect(const QObject *, const char *,const QObject *, const char *,Qt::ConnectionType);

QMetaObject::Connection connect(const QObject *, const QMetaMethod &,const QObject *, const QMetaMethod &,Qt::ConnectionType);

QMetaObject::Connection connect(const QObject *, const char *,const char *,Qt::ConnectionType) const;

QMetaObject::Connection connect(const QObject *, PointerToMemberFunction,const QObject *, PointerToMemberFunction,Qt::ConnectionType)

QMetaObject::Connection connect(const QObject *, PointerToMemberFunction,Functor);
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注：Functor类型：这个类型可以接受 static 函数、全局函数以及 Lambda 表达式。

2. qDebug()<<"" //类似cout的标准输出

信息槽

信息槽机制，通过QObject::connect()函数实现。

自定义信息槽。

注意：

（1）只有继承了QObject类的类，才具有信号槽的能力

（2）凡是QObject类（不管是直接子类还是间接子类），都应该在第一行代码写上Q_OBJECT，这个宏应该放在头文件中。

（3）实例

//!!! Qt5
#include <QObject>

////////// newspaper.h
class Newspaper : public QObject
{
    Q_OBJECT
public:
    Newspaper(const QString & name) :
        m_name(name)
    {
    }

    void send()
    {
        emit newPaper(m_name);
    }

signals:
    void newPaper(const QString &name);

private:
    QString m_name;
};

////////// reader.h
#include <QObject>
#include <QDebug>

class Reader : public QObject
{
    Q_OBJECT
public:
    Reader() {}

    void receiveNewspaper(const QString & name)
    {
        qDebug() << "Receives Newspaper: " << name;
    }
};

////////// main.cpp
#include <QCoreApplication>

#include "newspaper.h"
#include "reader.h"

int main(int argc, char *argv[])
{
    QCoreApplication app(argc, argv);

    Newspaper newspaper("Newspaper A");
    Reader reader;
    QObject::connect(&newspaper, &Newspaper::newPaper,
                     &reader,    &Reader::receiveNewspaper);
    newspaper.send();

    return app.exec();
}
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原文：https://blog.csdn.net/u014451076/article/details/51125338