How to create QTCPSocket object with nextPendingConnection?

[pratsam]

get the error:

> QIODevice::write (QTcpSocket): device not open.
After trying , I think problem is passing parameter server->nextPendingConnection() into object. Can someone has idea how to do it correctly?

My understanding is that object for `socketClient` is not initialised properly.
I'm using Ubuntu with Qt.

I am implementing server using Qt. The server part has two classes based on `QTcpServer` and `QTcpSocket`.
say `Server` and `SocketClient`.
I am creating object of SocketClient in server and for testing purpose I opened telnet session and wants to see that server write "hello" on terminal. But somehow its not working. Can someone please advice me where I am making mistake.

Server::Server(QObject *parent) : QObject(parent)
    {
      server_obj = new QTcpServer( this ); 
    }
 
    void Server::startServer()
    {
      connect( server_obj, SIGNAL( newConnection() ), this, SLOT( incomingConnection() ) );
      if( !server_obj->listen( QHostAddress::Any, 9999) )
      {
        qDebug() << " Server failed to get started";
      }
      else
      {
       qDebug() << " Server started"; // this is successful
      }
    }
 
 
    void Server::incomingConnection()
    {
      socketforClient = new SockClient( server_obj->nextPendingConnection() );// has a doubt on nextPendingconection?? May be Problem HERE..
 
      //only for testing remove it
      socketforClient->writeToClient();
    }

Server::Server(QObject *parent) : QObject(parent)
    {
      server_obj = new QTcpServer( this ); 
    }
    
    void Server::startServer()
    {
      connect( server_obj, SIGNAL( newConnection() ), this, SLOT( incomingConnection() ) );
      if( !server_obj->listen( QHostAddress::Any, 9999) )
      {
        qDebug() << " Server failed to get started";
      }
      else
      {
       qDebug() << " Server started"; // this is successful
      }
    }
    
    
    void Server::incomingConnection()
    {
      socketforClient = new SockClient( server_obj->nextPendingConnection() );// has a doubt on nextPendingconection?? May be Problem HERE..
    
      //only for testing remove it
      socketforClient->writeToClient();
    }

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Class for Client

* Description: Its a constructor.I have changed default constructor to add QTcpSocket* object in parameter.I used this constructor in  void Server::incomingConnection()
     */
    SockClient::SockClient(QObject *parent,QTcpSocket* socket ) : QObject(parent)
    {
      socketClient = new QTcpSocket( socket ); // PROBLEM HERE ?
 
     qDebug() << " we are in constructor of 1st sockclient ";
 
    }
 
 
 
    // this is for testing purpose only
 
    void SockClient::writeToClient()
    {
       socketClient->write(" hello world\r\n");
       socketClient->flush();
       socketClient->waitForBytesWritten(3000);
 
    }

* Description: Its a constructor.I have changed default constructor to add QTcpSocket* object in parameter.I used this constructor in  void Server::incomingConnection()
     */
    SockClient::SockClient(QObject *parent,QTcpSocket* socket ) : QObject(parent)
    {
      socketClient = new QTcpSocket( socket ); // PROBLEM HERE ?
    
     qDebug() << " we are in constructor of 1st sockclient ";
    
    }
    
    
    
    // this is for testing purpose only
    
    void SockClient::writeToClient()
    {
       socketClient->write(" hello world\r\n");
       socketClient->flush();
       socketClient->waitForBytesWritten(3000);
    
    }

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//header file of SockClient

class SockClient : public QObject
    {
      Q_OBJECT
    public:
 
     explicit  SockClient( QObject *parent, QTcpSocket* socket= 0 ); // I have created
        void writeToClient(); // This is for testing purpose
     ~SockClient();
    signals:
 
    private slots:
      void readClient();
 
    private:
      void sendResponsetoMops();
 
      QTcpSocket *socketClient;
 
      quint16 nextBlockSize;
 
    public slots:
    };

class SockClient : public QObject
    {
      Q_OBJECT
    public:
    
     explicit  SockClient( QObject *parent, QTcpSocket* socket= 0 ); // I have created
        void writeToClient(); // This is for testing purpose
     ~SockClient();
    signals:
    
    private slots:
      void readClient();
    
    private:
      void sendResponsetoMops();
    
      QTcpSocket *socketClient;
    
      quint16 nextBlockSize;
    
    public slots:
    };

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[ChrisW67]

QTcpServer::nextPendingConnection() returns an open QTcpSocket connected to the client. Why are you trying to create another one? This other socket you never connect or open...

[anda_skoa]

And you never use the socket returned by nextPendingConnection(), you are passing it as the parent of SockClient.

Cheers,
_

[wojiaoguowei]

void Server::incomingConnection()
{
QTcpSocket *newsocket = m_tcpServer->nextPendingConnection();

connect(newsocket,SIGNAL(readyRead()),this,SLOT(re adyRead()));
}