write to Qfile adds additional byte

mobo

I am programming a tool in Qt in which I want to write binary data into a file. Everything works fine except when I am trying to write the decimal value '10' (0000 1010 in binary) into the file. in this case I get an additional byte with the value '0000 1101' in front of the other byte. It doesn't matter how much data I write in the file, as soon as I write a 10 I get another byte.

I broke it down to the following code:

#include <QCoreApplication>
#include <QFile>
#include <iostream> 
#include <QString>
#include <QDataStream>

int main(int argc, char *argv[])
{
 QCoreApplication a(argc, argv);

 QString SavePath;
  SavePath = qApp->applicationDirPath();
  SavePath.append("/test.bin");

  QFile file(SavePath.toLocal8Bit().constData());
  if (file.exists())
      file.remove();
  if (!file.open(QIODevice::WriteOnly | QIODevice::Text))
  {
    return -1;
  }

  QDataStream out(&file);
  out.setVersion(QDataStream::Qt_4_3);
  out.setByteOrder(QDataStream::LittleEndian);
  out << qint32(10);

  int test=10;
  out.writeRawData((char*)&test,4 );

  file.write((char*)&test);

  return 1;
 }

The output in my file is:

 0d 0a 00 00 00 0d 0a 00 00 00 0d 0a

the three 0x0d bytes are unwanted. I don't get them while writing a '9' or an '11' to the file. I am running out of ideas. Can anyone tell me what I am doing wrong?

mrjj

Hi
QDataStream handles byte order for you
so i think it is adding info to allow this.
You use other write methods, ( i think)
http://doc.qt.io/qt-5/qdatastream.html#raw

m.sue

Hi,
you should open a binary file without QIODevice::Text.
-Michael.

mobo

Hi mrjj,
thanks for your answer!
Yes I read about the possibility that QDataStream might add additional informations. Therefore in addition to the normal << operator I also tried the writeRawData funkction of QDataStream and the normal write function of QFile. I got the same results with all three ways.

mrjj

@mobo
Hi
Ok, then something else is wrong.
Maybe @m-sue answer will help.

mobo

Thanks m.sue,

that solved it!
I deleted the QIODevice::Text in the open function and everything is fine!

mrjj

@mobo
ok so it was adding newline or something like that?

mobo

Yes, it add CR(0x0D) symbol to LF(0x0A) symbol in Windows.

How do I mark this as solved? With the topic tool button I can only delete this topic.. Is that, because I am a newbie here?

mrjj

@mobo
Nope, we loooove newbies here :)

You must first select Ask as question and then it can be Solved.
(yep its NOT clear )

Update:
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write to Qfile adds additional byte