Add example project.

main.cpp

@@ -0,0 +1,43 @@
+#include <QApplication>
+#include <QMainWindow>
+#include <QPushButton>
+#include <QLabel>
+#include <QVBoxLayout>
+
+int main(int argc, char *argv[]) {
+    QApplication app(argc, argv);
+
+    QMainWindow mainWindow;
+    mainWindow.setWindowTitle("Hello World Qt");
+    mainWindow.resize(400, 300);
+
+    // Create central widget and layout
+    QWidget *centralWidget = new QWidget(&mainWindow);
+    QVBoxLayout *layout = new QVBoxLayout(centralWidget);
+
+    // Create hello world label
+    QLabel *helloLabel = new QLabel("Hello World!", centralWidget);
+    helloLabel->setAlignment(Qt::AlignCenter);
+    helloLabel->setStyleSheet("font-size: 24px; font-weight: bold;");
+
+    // Create close button
+    QPushButton *closeButton = new QPushButton("Close", centralWidget);
+    closeButton->setStyleSheet("font-size: 16px; padding: 10px;");
+
+    // Connect button to close action
+    QObject::connect(closeButton, &QPushButton::clicked, &mainWindow, &QMainWindow::close);
+
+    // Add widgets to layout
+    layout->addStretch();
+    layout->addWidget(helloLabel);
+    layout->addWidget(closeButton);
+    layout->addStretch();
+
+    // Set central widget
+    mainWindow.setCentralWidget(centralWidget);
+
+    // Show the window
+    mainWindow.show();
+
+    return app.exec();
+}