QDataStream writing wrong values

[ChrisW67]

Please let me know how to address this problem

There is no problem. QDataStream is outputting exactly what you asked it to. You have a 32-bit unsigned integer with the value 54 and you have asked for output in LittleEndian order. The integer is 4 bytes 0x00000036, and QDataStream outputs them in reverse order. You get 4 bytes in the file, the first is 54 decimal (0x36) followed by 3 zero bytes. Treated as text this is equivalent to the C string "6".

const int num = 54;
 
QFile out("out.txt");
if (out.open(QIODevice::WriteOnly) {
  QTextStream s(&out);
  s << num;
}

const int num = 54;

QFile out("out.txt");
if (out.open(QIODevice::WriteOnly) {
  QTextStream s(&out);
  s << num;
}

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Also look at QString::number(), QByteArray::number() etc.