QNetworkReply::finished lambda QFile::open switch crash

[sonichy]

void FtpManager::get(const QString &path, const QString &fileName)
{
    m_pUrl.setPath(path);
    QNetworkReply *pReply = m_manager.get(QNetworkRequest(m_pUrl));
    //connect(pReply, SIGNAL(finished()), this, SLOT(finished()));
    connect(pReply, &QNetworkReply::finished, [&, pReply]() {
        qDebug() << pReply->errorString();
        switch (pReply->error()) {
        case QNetworkReply::NoError :{
            QFile m_file;
            m_file.setFileName(fileName);
            m_file.open(QIODevice::WriteOnly);
            m_file.write(pReply->readAll());
            m_file.flush();
            m_file.close();
            break;}
        default:
            break;
        }
        pReply->deleteLater();
    });
}

[jsulm]

@sonichy Use debugger

[Christian Ehrlicher]

@sonichy said in QNetworkReply::finished lambda QFile::open switch crash:

fileName

this variable is out of scope due to [&] - C++ basics

[JonB]

@christian-ehrlicher
I presume you are talking about the & in [&, pReply](). For those of us unaware of this C++ lambda syntax, could you point to a reference explaining, please?

[Christian Ehrlicher]

@JonB: @J-Hilk explained it some hours ago here: https://forum.qt.io/topic/106751/connecting-to-statusbar-showmessage-gives-compile-time-error-in-new-syntax/11 and searching for c++11 lambda will show you e.g. https://en.cppreference.com/w/cpp/language/lambda#Lambda_capture which should be read before someone is using a lambda.

[sonichy]

@christian-ehrlicher Fixed !

connect(pReply, &QNetworkReply::finished, [=]() {
      ......
}

[J.Hilk]

@sonichy did you read the thread or the article, that @Christian-Ehrlicher linked?

From either you should be able to deduce, how to capture filename by value instead of reference

[JonB]

@j-hilk , @Christian-Ehrlicher
No, I didn't spot that link somehow, now I do, and I see it explains. So that's what I was looking for. I shall add this new & to the = for the (tortured) list of new "overloaded operator symbols with different meanings" that C++ wants me to remember... ;-)