初始qt

day10/qtdemo0/main.cpp

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+#include "widget.h"
+
+#include <QApplication>
+
+int main(int argc, char *argv[])
+{
+    // 1. Qt 应用程序
+    QApplication a(argc, argv);
+
+    // 2. 应用程序中显示的主窗口
+    Widget w;
+    w.show();
+
+    // 3. 启动 Qt 程序, 监听窗口的相关事件
+    // 直到窗口关闭事件发生才退出
+    return a.exec(); // a.exec 的目的是保持程序活着
+}

day10/qtdemo0/qtdemo0.pro

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+QT       += core gui
+
+greaterThan(QT_MAJOR_VERSION, 4): QT += widgets
+
+CONFIG += c++11
+
+# The following define makes your compiler emit warnings if you use
+# any Qt feature that has been marked deprecated (the exact warnings
+# depend on your compiler). Please consult the documentation of the
+# deprecated API in order to know how to port your code away from it.
+DEFINES += QT_DEPRECATED_WARNINGS
+
+# You can also make your code fail to compile if it uses deprecated APIs.
+# In order to do so, uncomment the following line.
+# You can also select to disable deprecated APIs only up to a certain version of Qt.
+#DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000    # disables all the APIs deprecated before Qt 6.0.0
+
+SOURCES += \
+    main.cpp \
+    widget.cpp
+
+HEADERS += \
+    widget.h
+
+# Default rules for deployment.
+qnx: target.path = /tmp/$${TARGET}/bin
+else: unix:!android: target.path = /opt/$${TARGET}/bin
+!isEmpty(target.path): INSTALLS += target

day10/qtdemo0/widget.cpp

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+#include "widget.h"
+#include <QApplication>
+#include <QPushButton>
+
+Widget::Widget(QWidget *parent)
+    : QWidget(parent)
+{
+    this->setWindowTitle("我是第一个小窗口");
+
+    //    this -> resize(200,300);
+
+    this->setFixedSize(QSize(480, 320));
+
+    // 创建一个按钮
+    // c++中创建类对象的两种方式:
+    // 1) 类名 对象 (构造函数的)
+    QPushButton *btn = new QPushButton("退出");
+    btn->resize(100, 50); // 设置控件的大小
+    btn->setParent(this); // 设置控件在哪一个窗口显示
+
+    btn->move(190, 135);
+
+    // connect(btn,&QPushButton::clicked,this,&QApplication::quit);
+    connect(btn, &QPushButton::clicked, this, &QWidget::close);
+
+    QPushButton *btn2 = new QPushButton("2");
+    btn2->resize(100, 50); // 设置控件的大小
+    btn2->setParent(this); // 设置控件在哪一个窗口显示
+
+    btn2->move(190 + 100, 135);
+
+    QPushButton *btn3 = new QPushButton("3");
+    btn3->resize(100, 50); // 设置控件的大小
+    btn3->setParent(this); // 设置控件在哪一个窗口显示
+
+    btn3->move(190 + 200, 135);
+}
+
+Widget::~Widget()
+{
+}

day10/qtdemo0/widget.h

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+#ifndef WIDGET_H
+#define WIDGET_H
+
+#include <QWidget>
+
+class Widget : public QWidget
+{
+    Q_OBJECT
+
+public:
+    Widget(QWidget *parent = nullptr);
+    ~Widget();
+};
+#endif // WIDGET_H