What is the difference between delete and deleteLater

w.tkm

I wonder the difference between delete and deleteLater.
I try to use these in my code, but My app was call SIGSEGV when I used [delete].

It code:

void CcuTcp::fnReconnectTcp(QString sTcpConnectIP, quint16 uiTcpConnectPort, QString sTcpBindIP)
{

    if( m_pTcpSocket != nullptr ) {
        m_pTcpSocket->close();
        //delete m_pTcpSocket;               //call SIGSEGV
        m_pTcpWifiSocket->deleteLater();     //no call SIGSEGV
    }

    m_pTcpSocket = new QTcpSocket();
    fnTcpClientSet( sTcpConnectIP, uiTcpConnectPort, sTcpBindIP);
}

This code is a function for reconnecting the Tcp client.
It work automatically if the server is not found or is lost.

If I use [delete], After a few seconds, SIGSEGV will be called.
But if I use [deleteLate],SIGSEGV will not be called.

What is the difference between the two?
Also, is it better to use deleteLater in other situations as well?(For example, in Destructor)

SGaist

Hi,

delete is the standard C++ deletion instruction that will nuke the object right now.

deleteLater schedules the object deletion trough the event loop. See its documentation for more details.

KroMignon

@w-tkm said in What is the difference between delete and deleteLater:

I wonder the difference between delete and deleteLater.
I try to use these in my code, but My app was call SIGSEGV when I used [delete].

I think you could find all information in documentation => https://doc.qt.io/qt-5/qobject.html#deleteLater.

In short: with delateLater() the object will be destroyed on next event loop iteration, this will ensure all attached signals/slots for this instance will be nicely handled.

[EDIT] @SGaist was faster ;)

w.tkm

Oh, I know! thanks!
When I used delete, some signals/slots were not nicely handled.

Thank you, both of you.