Converting valid QFile to QString - QString is empty

Question

So I am trying to convert a QFile into a QString by doing the following:

void MainWindow::openTemplateFile(QString location)
{
    if (location.isEmpty())
        return;
    else
    {
        QString variable;
        templateFile.setFileName(location);
        if (!templateFile.open(QFile::ReadOnly | QFile::Text))
        {
            QMessageBox::information(this, "Unable to open template", 
            templateFile.errorString());
            return;
        }

        else    // file opened and ready to read from
        {
            QTextStream in(&templateFile);
            QString fileText = in.readAll();
            qDebug() << templateFile.size() << in.readAll();
        }
    }
}

However, in I get the following result in the debug console:

48 ""

templateFile does exist and is part of the MainWindow class. This is also simplified code - in the actual program I read chars from the file and it works correctly. The location string is a result of the QFileDialog::getOpenFileName function, which I open a txt file with.

Two comments: (1) the readAll() method has no way to report errors, and (2) the method returns a QByteArray (not a QString), and that QString constructor will stop at the first "0" in the array. If there are bytes of "0", the string will be shorter. — bnaecker
– bnaecker, Commented Nov 7, 2017 at 1:07
@bnaecker so how would you efficiently read a QFile’s contents to a QString? — James A
– James A, Commented Nov 7, 2017 at 1:10
@bnaecker The OP calls QTextStream::readAll(), not QFile::readAll(). The former does too return a QString — Igor Tandetnik
– Igor Tandetnik, Commented Nov 7, 2017 at 1:11

Igor Tandetnik · Accepted Answer · 2017-11-07 01:12:30Z

1

You call readAll() twice. The second time, the stream is positioned at end-of-file, and so readAll() has nothing to read and returns an empty string. Print fileText in your debug output instead.

answered Nov 7, 2017 at 1:12

Igor Tandetnik

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1 Comment

James A Over a year ago

Yeah, I understand that. This was just some messy debugging

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