Qt binary file writing and reading

[seniorc]

Hello,
@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

im working huffman encode project.I have all i needs(freq table,char code...)but i was writing code i cant earning size.I think this problem reason is opened binary and writing problem.How can i opened binary file and writing variables bytes.

for example;
@int x=4;
QString abc="hello";
char ch ='a';@
How can i writing them file.Thanks for all helping now.