udpsocket cannot bind,

[saman_artorious]

I am running a udpsocket client program which writes to and reads from server. when I run it, bind() returns false. Although I can still send data but I am wondering why sockets cannot bind and trigger readState slot.

As I checked a udp client does not bind, so I only set the port when initialized it. later I write like this:

void UDP::UDPInit(int port)
{
    socketPort = port;  
    udpsocket = new QUdpSocket(this);
}

void UDP::UDPInit(int port)
{
    socketPort = port;  
    udpsocket = new QUdpSocket(this);
}

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void UDP::sendCommand(QByteArray data)
{   
    if(udpsocket->writeDatagram(data.data(),QHostAddress(ip),socketPort)==-1)
        emit clientLogMessage(QString("UDPCLIENT : Write problem !"));
    else
        udpsocket->flush();
 
    //    QByteArray datagram;
    //    int m = udpsocket->read(datagram.data(), 11);
    //    qDebug() << errno;  
    //    qDebug() << m;
 
    while (!udpsocket->hasPendingDatagrams()) {
        QByteArray datagram;
        datagram.resize(udpsocket->pendingDatagramSize());
        qDebug() << udpsocket->pendingDatagramSize();
        udpsocket->readDatagram(datagram.data(), datagram.size());
        emit dataReceived(datagram);
    }
}
 
but the result is  -1 and it does not read anything from it. WHY? how can I solve this problem?

void UDP::sendCommand(QByteArray data)
{   
    if(udpsocket->writeDatagram(data.data(),QHostAddress(ip),socketPort)==-1)
        emit clientLogMessage(QString("UDPCLIENT : Write problem !"));
    else
        udpsocket->flush();
    
    //    QByteArray datagram;
    //    int m = udpsocket->read(datagram.data(), 11);
    //    qDebug() << errno;  
    //    qDebug() << m;
    
    while (!udpsocket->hasPendingDatagrams()) {
        QByteArray datagram;
        datagram.resize(udpsocket->pendingDatagramSize());
        qDebug() << udpsocket->pendingDatagramSize();
        udpsocket->readDatagram(datagram.data(), datagram.size());
        emit dataReceived(datagram);
    }
}

but the result is  -1 and it does not read anything from it. WHY? how can I solve this problem?

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