qt binary file writing and reading

Question

void write(QString filename) {
  QChar ch('b');
  QFile mfile(filename);
  if (!mfile.open(QFile::WriteOnly) {
    qDebug() << "Could not open file for writing";
    return;
  }
  QDataStream out(&mfile);
  out.setVersion(QDataStream::Qt_4_8);
  out << ch;
  mfile.close();
}

open binary file and writing 'b'(binary)

void read(QString filename) {
  QFile mfile(filename);
  if (!mfile.open(QFile::ReadOnly)) {
    qDebug() << "Could not open file for reading";
    return;
  }
  QDataStream in(&mfile);
  in.setVersion(QDataStream::Qt_4_8);
  QChar mT;
  in >> mT;
  qDebug() << mT;
  mfile.close();
}

read but not mT='b'.if ch and mT variables are int always mT=4 why?How can i writing ch(binary file) and read from binary file

Answer 1

the 4 number is the length of your data. QDataStream store length of your data before it to indicate how many bytes need to read to gain the written data. your data has been written after it.