[Interest] reading from and writing to a file with QDataStream

[Sina Dogru]

Hello,

I am trying to read from and write to a file. But to do this, I use
QByteArray to pass it between some of the modules. But seems like things
does not work like I predicted.

Simply, on module A, I write some informations to a QByteArray. Then I pass
it to module B which writes to a file, and I do it for a bunch of times.

But when I try to read from this file, something goes wrong.

Here is a simplified version of what am I trying to do.

#include <QFile>
#include <QDataStream>
#include <QByteArray>
#include <QDebug>

int main()
{
    // module A creates a byte array
    QByteArray bai;
    QDataStream out(&bai, QIODevice::WriteOnly);
    out << QString("A QString"); // writes some information on it

    // passing bai to module A
    // module A do something...

    QFile file("file.dat");
    file.open(QIODevice::WriteOnly);

    QDataStream out2(&file); // and module A write those datas to a file.
    out2 << bai.size();
    out2 << bai;

    // and module B starts
    if (file.isOpen())
        file.close();

    file.open(QIODevice::ReadOnly);
    QDataStream in(&file);

    QString str;
    int a;                  // extracts size information
    in >> a >> str;         // extracts QString
    file.close();

    qDebug() << str << a; // output: "\u0000\u0012A QString" 22
    return 0;
}

I guess using QByteArray get things messed up. But then is there any advice
to pass the information to another function?

Thank you,
Sina
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