Getting Started with TCP Local Area Network (LAN) Communication in Qt

When it comes to TCP LAN communication in Qt, it’s important to start with some fundamental concepts and steps:

1. Qt Networking Module: Qt provides a set of classes and modules for network communication, including QTcpSocket and QTcpServer, which allow you to easily create TCP client and server applications.

Steps to Create a TCP LAN Communication:

1. Create a Qt Application

First, create a Qt application. You can use Qt Creator to create a new project or manually create a project using Qt’s command-line tools.

2. Include Qt Networking Module

In your Qt project, make sure to include the headers for the networking module:

#include <QTcpSocket>
#include <QTcpServer>
#include <QDebug>

3. Create a TCP Server

To create a TCP server, you need to use the QTcpServer class. Create an instance of QTcpServer in your application and bind it to a specific IP address and port:

QTcpServer* server = new QTcpServer(this);
if (!server->listen(QHostAddress::Any, 12345)) {
    qDebug() << "Server could not start!";
} else {
    qDebug() << "Server started on port 12345";
}

This example creates a TCP server that listens on all available IP addresses on port 12345. You can change the IP address and port as needed.

4. Handle Connection Requests

Use the newConnection() signal of QTcpServer to handle incoming client connection requests. This signal is emitted when a new client connects to the server. You can write a slot function to handle the connection.

connect(server, &QTcpServer::newConnection, this, &MyServer::newClientConnection);

In the newClientConnection slot function, you can accept the new connection and create a QTcpSocket to communicate with the client.

5. Create a TCP Client

To create a TCP client, you need to use the QTcpSocket class. Create an instance of QTcpSocket and connect to the server:

QTcpSocket* socket = new QTcpSocket(this);
socket->connectToHost("server_ip_address", 12345);

In the above code, replace “server_ip_address” with the IP address of your server.

6. Send and Receive Data

Use the write() function of QTcpSocket to send data and the readyRead() signal and read() function to receive data. Both server and client need to handle these operations.