Why isn't this joining files correctly?

[tom989]

I'm trying to join two or more files together.

For each new file to add I call this function:

void MainWindow::mergemp3(QString fname)              //fname is the new file to add
{
 
 
    QFile mp3name (fname);
    mp3name.open(QIODevice::ReadOnly);
 
 
    QByteArray temp= mp3name.readAll();
    mergedaudio +=temp;                                       //mergedaudio is a global qbytearray which is the resulting joined up file
 
 
}

void MainWindow::mergemp3(QString fname)              //fname is the new file to add
{


    QFile mp3name (fname);
    mp3name.open(QIODevice::ReadOnly);
    

    QByteArray temp= mp3name.readAll();
    mergedaudio +=temp;                                       //mergedaudio is a global qbytearray which is the resulting joined up file


}

To copy to clipboard, switch view to plain text mode 

Then I write out the merged file:

QFile test("testout.mp3");
    test.open(QIODevice::WriteOnly);
    QDataStream writetest(&test);
    writetest<< mergedaudio;

QFile test("testout.mp3");
    test.open(QIODevice::WriteOnly);
    QDataStream writetest(&test);
    writetest<< mergedaudio;

To copy to clipboard, switch view to plain text mode 

The resulting file (mp3) doesn't play correctly. I know this can be done as I used standard c++ to do it.

Any idea what I've done wrong?

---

Added after 5 minutes:

Oops. Was using the << which is for formatted data.

[ChrisW67]

QDataStream is the wrong tool for this job and completely unnecessary: just use QIODevice::write();

[amleto]

surely you end up with two ID3 tags in the merged file - one somewhere in the middle of the file! Isn't this a problem?