how to read and parse hex value data from text file

[KARMA]

I have a text file where i store my hex data.
I store every package I receive from the serial, line by line.

The records in the text file are as follows;
ffc48e3a0105038484848484848484
ffb88f3a0105038403000000000000

my code is as follows;

   QString filename= QFileDialog::getOpenFileName(this, "Choose File");
   QFile file(filename);

    if(filename.isEmpty())
    {
        return;
    }
    else if(!file.open(QIODevice::ReadWrite | QIODevice::Text))
    {
       return;
    }
    else
    {
        QByteArray ba = file.readAll();
    }

When I read the file, it saves it in qbytearray like this;

but I want it to save 2 letters instead of one letter in each index.

for example;
ba[0] = ff;
ba[1] = 07;

can you help me how to do it?

[J.Hilk]

@KARMA change your debug display

[KARMA]

@J-Hilk I did, but nothing changed in the view.
QByteArray puts each letter in a different index. I don't want this to happen because every 2 letters is a hex data.

[J.Hilk]

@KARMA than the normal debug plane is not the right place for you, you'll need to write something your self and output it to the console or something like that

[KARMA]

@J-Hilk this is not the problem.
"ff" is my packet head.
Since "ff" is in separate indexes as 0 and 1, I cannot parse it.
if i do pckt=ba[0] i just get the letter f.
If I do memcpy(&pckt,&ba.data[0],2) I get a different value than 255. because ff isn't actually 1 byte not 2 byte.

[J.Hilk]

@KARMA said in how to read and parse hex value data from text file:

@J-Hilk this is not the problem.
"ff" is my packet head.
Since "ff" is in separate indexes as 0 and 1, I cannot parse it.
if i do pckt=ba[0] i just get the letter f.
If I do memcpy(&pckt,&ba.data[0],2) I get a different value than 255. because ff isn't actually 1 byte not 2 byte.

no,

F is a nibble, aka 4 bit
FF is a byte aka 8 bit
QByteArray stores internally a char array. char = 8 bit = 1 byte = int8_t

[KARMA]

@J-Hilk so how do i do that? for example I need to copy the first 4 bytes after ff to uint32, but when stored this way I can't. how should i go about it?

[JonB]

@KARMA said in how to read and parse hex value data from text file:

I store every package I receive from the serial, line by line.

Since you say, and show, "line by line", you will have to deal with (skip) the newlines/line breaks anyway. With readAll() you will have to do that, apart from having to go through a pair of bytes at a a time.

You might prefer to wrap the QFile into a QTextStream so that you can use QString QTextStream::readLine() repeatedly to get each line with the newline removed. That's a QString, so you can go through it 2 characters at a time for your pairs of hex characters.

Given a pair of characters, e.g. "ff" or "07", you can then use int QString::toInt(nullptr, 16) const to get the numeric value 0--255/0x00--0xFF of the character pair, if you need that, which it sounds like you do.

Of course, if you don't want to do it via all these Qt methods you can always convert a pair of hexadecimal digit characters/bytes to the hex number yourself, with a single line of subtraction, multiplication and addition....

[mpergand]

    QByteArray data("ffc48e3a0105038484848484848484");  //  the data are in hexa string representation
    QByteArray bin=QByteArray::fromHex(data);   // convert to binary

    QBuffer buffer(&bin);
    buffer.open(QBuffer::ReadWrite);
    QDataStream stream(&buffer);

    stream.skipRawData(1);      // skip first byte ff
    uint32_t v1;
    stream>>v1;      // read uint32
    // assuming the next data is an int16 as an example
    int16_t v2;
    stream>>v2;      // read int16
    etc ...

    qDebug()<<v1<<v2;   // 3297655297 1283

You may have to consider endianess, here big endian (default)
see setByteOrder(QDataStream::ByteOrder bo)

[JonB]

@mpergand said in how to read and parse hex value data from text file:

QByteArray bin=QByteArray::fromHex(data); // convert to binary

Sigh, forgot there is a QByteArray::fromHex(). So many little functions in Qt to keep in mind... :)

[KARMA]

@mpergand thank you so much. this worked great for me.
@JonB @J-Hilk thank you too