Why Use Qt with C++ for GUI Development?

Qt is a robust and mature cross-platform GUI framework that works seamlessly with C++. It provides tools, widgets, and libraries for building modern desktop applications with rich interfaces. Qt abstracts away the platform-specific details, allowing you to write code once and deploy it on Windows, macOS, and Linux. Combined with the performance and control of C++, Qt enables you to build responsive and powerful desktop apps that look native on every system.

Prerequisites

• Installed Qt Creator IDE (comes with the Qt framework): Download Qt
• Basic knowledge of C++ and object-oriented programming
• Familiarity with classes, functions, and basic control flow in C++

Step 1: Create a New Qt Project

Open Qt Creator and create a new project:

• Go to File → New File or Project
• Select Application → Qt Widgets Application
• Name it NotesApp and choose a location
• Click through the wizard, choosing your desired build kits

Qt Creator will generate a boilerplate Qt application with a main window class.

Step 2: Design the GUI

Open the file mainwindow.ui in Qt Designer. Add the following widgets:

• QTextEdit: for typing notes (drag from the widget box)
• QPushButton: label it “Save Note”

Arrange the widgets vertically using a Vertical Layout. This will make your layout flexible and resize-friendly.

Step 3: Implement the Save Logic

In mainwindow.h, add the following slot declaration inside the MainWindow class:

private slots:
    void saveNote();

Then open mainwindow.cpp and implement the slot function:

void MainWindow::saveNote()
{
    QString note = ui->textEdit->toPlainText();
    QFile file("notes.txt");
    if (file.open(QIODevice::Append | QIODevice::Text)) {
        QTextStream out(&file);
        out << note << "\n\n";
        file.close();
    }
}

This function reads the content from the text area and appends it to a file called notes.txt.

Step 4: Connect the Button to the Function

Still in mainwindow.cpp, inside the constructor after ui->setupUi(this);, add:

connect(ui->pushButton, &QPushButton::clicked, this, &MainWindow::saveNote);

This links the “Save Note” button to the saveNote() function so that notes are saved when clicked.

Step 5: Build and Run

Click the green Run button in Qt Creator or press Ctrl+R (or Cmd+R on Mac) to compile and launch your application. Type a note into the text box, click “Save Note,” and confirm that it appends to a notes.txt file in your project directory.

Step 6: Package Your App for Distribution

Qt provides tools to bundle your app with necessary libraries:

• For Windows, use windeployqt
• For macOS, use macdeployqt
• For Linux, create a shell script or AppImage package

This makes your app portable and ready to share without requiring users to install Qt.

Conclusion

You’ve now built a basic yet functional cross-platform desktop application using C++ and Qt. You created a GUI, handled user input, saved data to a file, and learned the foundation of Qt’s event system. With this knowledge, you can build more advanced apps like to-do lists, planners, and productivity tools with richer interfaces and persistent storage.