#include "widget.h"
#include "ui_widget.h"
//widget.cpp
Widget::Widget(QWidget *parent): QWidget(parent), ui(new Ui::Widget)
{ui->setupUi(this);//连接槽  ,触发对象和接收都是自己QObject::connect(this ,SIGNAL(mysignal()) ,this ,SLOT(myslot()));QObject::connect( this ,SIGNAL(mysignalparams(int)) ,this ,SLOT(myslotparams(int)) );emit mysignal();        //触发信号emit mysignalparams(999);   //触发带参数的信号
}Widget::~Widget()
{delete ui;
}void Widget::myslot()     //槽函数
{std::cout << "myslot" << std::endl;
}void Widget::myslotparams(int value)
{std::cout << "myslotparams ," << value << std::endl;qDebug() << "This is value = " << value;
}

//widget.h
#ifndef WIDGET_H
#define WIDGET_H#include <QWidget>
#include <iostream>
#include <QDebug>QT_BEGIN_NAMESPACE
namespace Ui { class Widget; }
QT_END_NAMESPACEclass Widget : public QWidget
{Q_OBJECTpublic:Widget(QWidget *parent = nullptr);~Widget();signals:            //自定义信号void mysignal();void mysignalparams(int value);public slots:       //自定义槽void myslot();void myslotparams(int value);private:Ui::Widget *ui;
};
#endif // WIDGET_H

       执行结果

5.2、例2

        创建两个类，比如Sender和Receiver。Sender类将发出信号，而Receiver类将接收并处理这个信号。

// Sender.h  
#ifndef SENDER_H  
#define SENDER_H  #include <QObject>  class Sender : public QObject {  Q_OBJECT  
public:  explicit Sender(QObject *parent = nullptr);  signals:      void mySignal();      //信号public slots:  void emitSignal();  
};  #endif // SENDER_H

// Sender.cpp  
#include "Sender.h"  Sender::Sender(QObject *parent) : QObject(parent) {  
}  void Sender::emitSignal() {  emit mySignal();          //发送信号
}

// Receiver.h  
#ifndef RECEIVER_H  
#define RECEIVER_H  #include <QObject>  
#include <QDebug>  class Receiver : public QObject {  Q_OBJECT  
public:  explicit Receiver(QObject *parent = nullptr);  public slots:  void handleSignal();      //槽函数
};  #endif // RECEIVER_H

// Receiver.cpp  
#include "Receiver.h"  Receiver::Receiver(QObject *parent) : QObject(parent) {  
}  void Receiver::handleSignal() {  qDebug() << "Signal received!";  //槽函数
}

// main.cpp  
#include <QCoreApplication>  
#include "Sender.h"  
#include "Receiver.h"  int main(int argc, char *argv[]) {  QCoreApplication a(argc, argv);  Sender sender;  Receiver receiver;  //连接信号与槽QObject::connect(&sender, &Sender::mySignal, &receiver, &Receiver::handleSignal);  sender.emitSignal(); // 调用函数发送信号return a.exec();  
}

6、QDebug()

qDebug() << "This is a debug message";
int value = 10;
qDebug() << "The value is" << value;