信号和槽的定义和使用

信号和槽的相关概念：

用信号和槽，实现一个功能：

1.定义teacher和student两个类（继承Qobject）； 2.teacher类发送信号hungry()，student类接受信号，用槽函数treat（）响应；

student类的.h代码

#ifndef STUDENT_H #define STUDENT_H #include <QObject> class student : public QObject { Q_OBJECT public: explicit student(QObject *parent = nullptr); signals: public slots: //请客的槽函数，用来响应teacher发来的hurry信号 //信号和槽函数的参数类型必须一一对应 void treat(); void treat(QString foodName); }; #endif // STUDENT_H

student类的.cpp代码

#include "student.h" #include <QDebug> student::student(QObject *parent) : QObject(parent) { } void student::treat(){ qDebug() << "老师吃饭了"; } void student::treat(QString foodName){ //将QString转换为char *p qDebug() << "老师要吃：" << foodName.toUtf8().data(); }

teacher类的.h代码

#ifndef TEACHER2_H #define TEACHER2_H #include <QObject> class teacher2 : public QObject { Q_OBJECT public: explicit teacher2(QObject *parent = nullptr); signals: //定义的信号 //只需要声明，不需要实现 void hungry(); void hungry(QString foodName); public slots: }; #endif // TEACHER2_H

teacher类的.cpp文件

#include "teacher2.h" teacher2::teacher2(QObject *parent) : QObject(parent) { }

widget.h代码

#ifndef MYWIDGET_H #define MYWIDGET_H #include <QWidget> #include "student.h" #include "teacher2.h" class myWidget : public QWidget { Q_OBJECT public: myWidget(QWidget *parent = 0); ~myWidget(); void class_over(); teacher2 * th; student *st; }; #endif // MYWIDGET_H

widget.cpp代码

#include "mywidget.h" #include<QPushButton> #include <QDebug> myWidget::myWidget(QWidget *parent) : QWidget(parent) { th = new teacher2(this); st = new student(this); //连接信号和槽,不带参数的 void (teacher2:: * teacher_signal1)(void) = &teacher2::hungry; void (student:: * student_slot1)(void) = &student::treat; connect(th, teacher_signal1, st, student_slot1); //信号连接信号 QPushButton* btn = new QPushButton; btn->setParent(this); btn->setText("下课了"); connect(btn, &QPushButton::clicked, th, teacher_signal1); class_over(); //连接带参数的信号和槽函数 void (teacher2:: *teacher_signal2)(QString) = &teacher2::hungry; void (student:: *student_slot2)(QString) = &student::treat; QPushButton* btn2 = new QPushButton("回锅肉"); btn2->setParent(this); btn2->move(100,100); connect(th, teacher_signal2,st, student_slot2); connect(btn2, &QPushButton::clicked, th, teacher_signal2); } void myWidget::class_over(){ //发送自定义的信号 //用emit关键字，触发hungry（）函数 emit th->hungry(); emit th->hungry(QString ("回锅肉")); } myWidget::~myWidget() { }