QFile - pos() not equal to sum of bytes read?

QJames

Hi,
I'm pretty new to qt (and c++ in general), so maybe this is not a qt specific "problem".
I have a binary file that I open and I read a few bytes. After that I read a few more bytes in a loop. Subsequently, as far as I understood, file.pos() should be equal to all the bytes I have read so far, but for a few files, there is a mismatch.

code snippet:

[CODE]
char buffer[255];
qint64 bytesRead;
QFile file(fileName);
if (!file.open(QIODevice::ReadOnly | QIODevice::Text)){
    qDebug() << "could not open" << fileName;
    return -1;
}
bytesRead = file.read(buffer, 16);
if(bytesRead != 16){
   qDebug() << "mismatch bytes read" << bytesRead << " != " << 16;
} 
if(file.pos() != 16){
   qDebug() << "mismatch" << file.pos() << " != " << 16;
}
...
for (int i = 0; i < 7; i++) {
   bytesRead = file.read(buffer, 24);
   ...
   if(bytesRead != 24){
      qDebug() << "mismatch bytes read" << bytesRead << " != " << 24;
   } 
   if(file.pos() != (16 + (i+1)*24)){
     qDebug() << "mismatch" << file.pos() << " != " << (16 + (i+1)*24);
    }
}
file.close()

and the output is

mismatch  185  !=  184

This happens not on all files, so I am wondering what I am doing wrong...
Any help or pointer is appreciated!

Pl45m4

@QJames

file.pos() returns the current position, not the sum of all bytes read.
Any chance that something went wrong in these [...] lines?

https://doc.qt.io/qt-5/qiodevice.html#pos

JonB

@QJames
You are opening for QIODevice::Text. I can't recall how each of pos() and read() count, you should check whether one counts e.g. \r\n as 1 while the other does not? Perhaps the difference between files is down to the "newline" recognition/counting? Certainly remove the QIODevice::Text and compare. IIRC, text read makes pos() only take on certain values/validity anyway, there's something in the docs...

QJames

@Pl45m4 said in QFile - pos() not equal to sum of bytes read?:

@QJames

file.pos() returns the current position, not the sum of all bytes read.
Any chance that something went wrong in these [...] lines?

https://doc.qt.io/qt-5/qiodevice.html#pos

sure, but it should be the same, shouldn't it? the position should move along with bytes written/read.

@JonB said in QFile - pos() not equal to sum of bytes read?:

@QJames
You are opening for QIODevice::Text. I can't recall how each of pos() and read() count, you should check whether one counts e.g. \r\n as 1 while the other does not? Perhaps the difference between files is down to the "newline" recognition/counting? IIRC, text read makes pos() only take on certain values/validity anyway, there's something in the docs...

thank you, that was it!!
Removing the QIODevice::Text flag solved it.