CODEWITHSUNDEEP
qtqtcpsocket
Theodore Tang
Theodore Tang

Reputation: 1021

How to connect to QTcpSocket error signal in Qt

I am trying to get the QTcpSocket error by using signal and slot. I did like this:

connect(clientConnection->tcpSocket, &QTcpSocket::error, this, &ClientInterface::displayError);

void ClientInterface::displayError()
{
    qDebug() << clientConnection->tcpSocket->error();
    qDebug() << clientConnection->tcpSocket->errorString();
}

but I got this error:

error: no matching function for call to 'ClientInterface::connect(QTcpSocket*&, , ClientInterface*, void (ClientInterface::*)())' connect(clientConnection->tcpSocket, &QTcpSocket::error, this, &ClientInterface::displayError);

I also tried to implement the slot with QAbstractSocket::SocketError parameter like this:
void displayError(QAbstractSocket::SocketError);
But it showed the same error.

Where did I do wrong?

Edit:

I tried to connect like this as the answer says:

connect(clientConnection->tcpSocket, QOverload<QAbstractSocket::SocketError>::of(&QAbstractSocket::error), this, &ClientInterface::displayError);

But I got this problem:

QObject::connect: Cannot queue arguments of type 'QAbstractSocket::SocketError' (Make sure 'QAbstractSocket::SocketError' is registered using qRegisterMetaType().)

Upvotes: 2

Views: 9298

Answers (2)

T. N.
T. N.

Reputation: 66

As already mentioned, you will need some overload magic and register QAbstractSocket::SocketError as metatype.

This is also descriped in the Qt docs:

Qt 5: http://doc.qt.io/qt-5/qabstractsocket.html#error

Qt 4.8 http://doc.qt.io/archives/qt-4.8/qabstractsocket.html#error

You may also use the SIGNAL(...) macro instead of the function pointer syntax to overcome this problem:

Example:

QObject::connect(clientConnection->tcpSocket, SIGNAL(error(QAbstractSocket::SocketError)),
this, SLOT(displayError(QAbstractSocket::SocketError)));

Upvotes: 1

Mohammad Kanan
Mohammad Kanan

Reputation: 4582

You need to overload the QAbstractSocket error:

connect(tcpSocket, QOverload<QAbstractSocket::SocketError>::of(&QAbstractSocket::error),

            this, &ClientInterface::displayError);

Upvotes: 3

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