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);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。
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(); }<
原文：https://blog.csdn.net/u014451076/article/details/51125338
