QT C++ Network Programming Video Tutorial using a Hello World Example
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Developing applications that used to communicate with other computer over the network is an interesting area in the filed of programming. With the introduction of QT C++ libraries , this task become less complicated compared to the network programming in the past . All you need to know is the basics of TCP/IP and how computers communicate over the network using TCP/IP protocol.

In this programming video tutorial , we will show you how to develop a basic Networking applications based on TCP/IP Library QTcpServer and QTcpSocket .

Watch the YouTube Video From the link below..


Main Source Code

Client Part

Dialog.h

#ifndef DIALOG_H
#define DIALOG_H

#include <QDialog>
#include < QTcpSocket >

namespace Ui {
class Dialog;
}

class Dialog : public QDialog
{
    Q_OBJECT

public:
    explicit Dialog(QWidget *parent = 0);
    ~Dialog();
     QTcpSocket *m_pClientsocket;
private slots:
    void displayError ( QAbstractSocket::SocketError socketError );

private slots:
    void on_pushButtonConnect_clicked();

    void on_pushButtonSend_clicked();

private:
    Ui::Dialog *ui;
};

#endif // DIALOG_H

Dialog.cpp

#include "dialog.h"
#include "ui_dialog.h"

#include <QMessageBox>

Dialog::Dialog(QWidget *parent) :
    QDialog(parent),
    ui(new Ui::Dialog)
{
    m_pClientsocket = new QTcpSocket(this);
    ui->setupUi(this);
}

Dialog::~Dialog()
{

    delete ui;
}

void Dialog::on_pushButtonConnect_clicked()
{
     m_pClientsocket->connectToHost(ui->textEditIP->toPlainText(),quint16(ui->textEditPort->toPlainText().toInt()) );
     connect(m_pClientsocket, SIGNAL(error(QAbstractSocket::SocketError)), this, SLOT(displayError(QAbstractSocket::SocketError)));

}

void Dialog::on_pushButtonSend_clicked()
{
    QString message = ui->textEditMesage->toPlainText().trimmed();

    // Only send the text to the chat server if it's not empty:
    if(!message.isEmpty())
    {
        m_pClientsocket->write(QString(message + " ").toUtf8());
    }

    // Clear out the input box so they can type something else:
    ui->textEditMesage->clear();

    // Put the focus back into the input box so they can type again:
     ui->textEditMesage->setFocus();
}

void Dialog::displayError ( QAbstractSocket::SocketError socketError )
{
    switch (socketError) {
         case QAbstractSocket::RemoteHostClosedError:
             break;
         case QAbstractSocket::HostNotFoundError:
             QMessageBox::information(this, tr("Fortune Client"),
                                      tr("The host was not found. Please check the "
                                         "host name and port settings."));
             break;
         case QAbstractSocket::ConnectionRefusedError:
             QMessageBox::information(this, tr("Fortune Client"),
                                      tr("The connection was refused by the peer. "
                                         "Make sure the fortune server is running, "
                                         "and check that the host name and port "
                                         "settings are correct."));
             break;
         default:
             QMessageBox::information(this, tr("Fortune Client"),
                                      tr("The following error occurred: %1.")
                                      .arg(m_pClientsocket->errorString()));
         }


}

main.cpp

#include "dialog.h"
#include <QApplication>

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    Dialog w;
    w.show();

    return a.exec();
}

Server Part

HelloWorldServer .h

#ifndef HELLOWORLDSERVER_H
#define HELLOWORLDSERVER_H

#include <QTcpServer>

#include "MainWindow.h"
class MainWindow;

class HelloWorldServer : public QTcpServer
{
public:

    Q_OBJECT

        public:
            HelloWorldServer(MainWindow* pHelloServer,QObject *parent=0);
        MainWindow* m_pHelloWindow;

        private slots:
            void readyRead();
            void disconnected();

        protected:
            void incomingConnection(int socketfd);

        private:
            QSet<QTcpSocket*> clients;


};

#endif // HELLOWORLDSERVER_H

HelloWorldServer.cpp

#include "helloworldserver.h"
#include <QTcpSocket>

HelloWorldServer::HelloWorldServer(MainWindow* pHelloServer,QObject *parent) : QTcpServer(parent)
{
    m_pHelloWindow=pHelloServer;
}

void HelloWorldServer::incomingConnection(int socketfd)
{
    QTcpSocket *client = new QTcpSocket(this);
    client->setSocketDescriptor(socketfd);
    clients.insert(client);

    m_pHelloWindow->addMessage("New client from: "+client->peerAddress().toString());

    connect(client, SIGNAL(readyRead()), this, SLOT(readyRead()));
    connect(client, SIGNAL(disconnected()), this, SLOT(disconnected()));
}

void HelloWorldServer::readyRead()
{
    QTcpSocket *client = (QTcpSocket*)sender();
    while(client->canReadLine())
    {
        QString line = QString::fromUtf8(client->readLine()).trimmed();
        //qDebug() << "Read line:" << line;
        m_pHelloWindow->addMessage(line);

    }
}

void HelloWorldServer::disconnected()
{
    QTcpSocket *client = (QTcpSocket*)sender();
    qDebug() << "Client disconnected:" << client->peerAddress().toString();

    clients.remove(client);


}

MainWindow.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>

#include "HelloWorldServer.h"

namespace Ui {
class MainWindow;
}
class HelloWorldServer;

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    explicit MainWindow(QWidget *parent = 0);
    ~MainWindow();
    void addMessage(QString Msg);
    HelloWorldServer* m_pBoxServer;

private slots:
    void on_pushButtonStart_clicked();

private:
    Ui::MainWindow *ui;
};

#endif // MAINWINDOW_H

MainWindow.cpp

#include "mainwindow.h"
#include "ui_mainwindow.h"

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);


}

MainWindow::~MainWindow()
{
    delete ui;
}

void MainWindow::on_pushButtonStart_clicked()
{
   m_pBoxServer= new HelloWorldServer(this);

    bool success = m_pBoxServer->listen(QHostAddress::Any, quint16(ui->textEditPort->toPlainText().toInt()));
    if(!success)
    {
        addMessage("Server failed...");

    }
    else
    {
        addMessage("Server Started...");
    }
}

void MainWindow::addMessage(QString Msg)
{

    ui->textEditStatus->setText(Msg);

}

main.cpp

#include "mainwindow.h"
#include <QApplication>

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    MainWindow w;
    w.show();

    return a.exec();
}





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Joined Date :14-Nov-2012
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