Question

Hi fellow stack overflowers,

I’m currently parsing a file which both contains text and binary data. Currently, I’m reading the file in following manner:

QTextStream in(&file);

int index = 0;
while(!in.atEnd()) {
    if (index==0) {
        QString line = in.readLine(); // parse file here
    } else {
        QByteArray raw_data(in.readAll().toAscii());
        data = new QByteArray(raw_data);
    }
    index++;
}

where data refers to the binary data I’m looking for. I’m not sure if this is what I want, since the QString is encoded into ascii and I have no idea if some bytes are lost.

I checked the documentation, and it recommends using a QDataStream. How can I combine both approaches, i.e. read lines with an encoding and also read the binary dump, after one line break?

Help is greatly appreciated!

Answer 1

This will do what you want.

QTextStream t(&in);
QString line;
QByteArray raw_data;
if(!in.atEnd()) {line = t.readLine();}
in.reset();
int lineSize = line.toLocal8Bit().size() + 1;
in.seek(lineSize);
if(!in.atEnd())
{
    int len = in.size() - lineSize;
    QDataStream d(&in);
    char *raw = new char[len]();
    d.readRawData(raw, len);
    raw_data = QByteArray(raw, len);
    delete raw;
}

PS: if file format is yours, it will be better to create file with QDataStream and write data with <<, read with >>. This way you can store QByteArray and QString in file without such problems.