Qt

Language: CPP

CLI/Utils

Qt was first developed by Haavard Nord and Eirik Chambe-Eng in 1991. It became widely popular for building desktop, mobile, and embedded applications due to its cross-platform capabilities and rich set of libraries. Qt supports modern C++ and integrates with QML for declarative UI design.

Qt is a comprehensive C++ framework for developing cross-platform applications and graphical user interfaces (GUIs). It provides tools for GUI design, event handling, networking, threading, and more.

Installation

linux: sudo apt install qt5-default qtcreator

mac: brew install qt

windows: Download Qt installer from https://www.qt.io/download

Usage

Qt provides modules for GUI, networking, multimedia, database access, and more. It follows an object-oriented and signal-slot architecture to handle events and interactions efficiently.

Simple GUI application

#include <QApplication>
#include <QLabel>

int main(int argc, char *argv[]) {
    QApplication app(argc, argv);
    QLabel label("Hello, Qt!");
    label.show();
    return app.exec();
}

Creates a basic Qt application with a window displaying 'Hello, Qt!'.

Button click with signal-slot

#include <QApplication>
#include <QPushButton>
#include <QObject>
#include <iostream>

int main(int argc, char *argv[]) {
    QApplication app(argc, argv);
    QPushButton button("Click Me");
    QObject::connect(&button, &QPushButton::clicked, [](){ std::cout << "Button clicked!" << std::endl; });
    button.show();
    return app.exec();
}

Demonstrates Qt's signal-slot mechanism by printing a message when a button is clicked.

Using Qt for networking

// Use QTcpSocket, QUdpSocket, or QNetworkAccessManager for network operations.

Multithreading in Qt

// Use QThread or QtConcurrent for running tasks in parallel.

Database access

// Use QSqlDatabase and QSqlQuery to connect and interact with SQL databases.

Error Handling

QSqlError: Check database connection, credentials, and SQL query syntax.

QNetworkReply error: Handle network errors by checking error codes and implementing retries.

Best Practices

Use signal-slot mechanism for event-driven programming instead of polling.

Keep UI code and business logic separate.

Use layouts instead of fixed coordinates for flexible GUI design.

Prefer modern C++ features when writing Qt applications.

Utilize Qt's resource system for managing assets like images and icons.

Official Docs Github