[C++知识库]QT基础-QT内存回收机制

参考Qt学习笔记(四)：Qt 的内存回收机制
在 Qt 中，QObject 是顶层对象，当 Qt 程序关闭的时候，QObject 对象会被自动释放掉


mainwindow.cpp

//
// Created by 宁彦吉 on 2022/2/1.
//
#include "../Headers/mainwindow.h"


MainWindow::MainWindow(QWidget *parent) : QMainWindow(parent) {
    this->resize(1600, 1200);
    // btn1间接继承QObject，btn2没有继承QObject
    btn1 = new Button1(this);
    btn2 = new Button2();
}

MainWindow::~MainWindow() {
    // 手动释放
    delete btn2;
    qDebug() << "程序关闭，父被释放";
}

mainwindow.h

//
// Created by 宁彦吉 on 2022/2/1.
//
#ifndef QT_CREATOR_TEST_MAINWINDOW_H
#define QT_CREATOR_TEST_MAINWINDOW_H

#include <QWidget>
#include <QMainWindow>
#include <QDebug>
#include "../Headers/button1.h"
#include "../Headers/button2.h"

class MainWindow : public QMainWindow {
Q_OBJECT
public:
    MainWindow(QWidget *parent = nullptr);

    ~MainWindow();

private:
    Button1 *btn1;
    Button2 *btn2;
};

#endif //QT_CREATOR_TEST_MAINWINDOW_H

button1.h

//
// Created by 宁彦吉 on 2022/2/1.
//

#ifndef QT_CREATOR_TEST_BUTTON1_H
#define QT_CREATOR_TEST_BUTTON1_H

#include <QPushButton>

class Button1 : public QPushButton {
Q_OBJECT
public:
    Button1(QWidget *parent = nullptr);

    ~Button1();
};

#endif //QT_CREATOR_TEST_BUTTON1_H

button1.cpp

//
// Created by 宁彦吉 on 2022/2/1.
//
#include "../Headers/button1.h"
#include <QDebug>

Button1::Button1(QWidget *parent) : QPushButton(parent) {

}

Button1::~Button1() {
    qDebug() << "Button1析构函数启动";
}

button2.h

//
// Created by 宁彦吉 on 2022/2/1.
//

#ifndef QT_CREATOR_TEST_BUTTON2_H
#define QT_CREATOR_TEST_BUTTON2_H

#include <QPushButton>

class Button2 : public QPushButton {
Q_OBJECT
public:
    Button2(QWidget *parent = nullptr);

    ~Button2();
};

#endif //QT_CREATOR_TEST_BUTTON2_H

button2.cpp

//
// Created by 宁彦吉 on 2022/2/1.
//
#include "../Headers/button2.h"
#include <QDebug>

Button2::Button2(QWidget *parent) : QPushButton(parent) {

}

Button2::~Button2() {
    qDebug() << "Button2析构函数启动";
}