redaing binary file

[anh5kor]

I have a requirement where I have to ready a binary file and search for a particular address given by user and store the hex value of corresponding address in an array.
I have a file like "39059921.HA". Which i have to read on a button click.
I have opened the file in hex viewer and the inside content are like below

Block 0 Strarts at:0x 0 Ends at: 0x4319 (Length:0x431A=17178)
00000000: 03 01 00 02 04 00 55 50 41 00 00 00 00 00 00 00 ......UPA.....
00000010: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 .................
00000020: FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF .................
00000030: 66 65 74 79 00 00 00 00 00 00 00 00 CD 38 1A D1 .fety........
-------
-------

I tried reading the file like normal text file but i am getting some junk value.

QFile file("39059921.HA");
 
    if(!file.open(QIODevice::ReadOnly | QIODevice::Text))
       {
           return;
       }
      QTextStream stream(&file);
      while(!stream.atEnd())
      {
          QString line = stream.readLine();
          qDebug()<<"data"<<line;
      }
 
      file.close();
 
output:-I get the output like below
data"
"—¶GÐEÐk|‘s‰žÃ*¥òm[ˆ8êܳ$7¢,HYNܾlFTÛ/õêÃâlÂ¥Bóîä1©»0*¢Ïƒ©è~Êßl«Ê2<ˆWXˆ³8{Èà IÃ…@" 
data"&ÓûcVp„êp1¡Çø–ڐñT77”(/•´„ŸÎµ°©¯”9·|ÞmJ"5²ŒBÂ¡ó” ˜NWeB(¯e£÷•ˆ^Ó$Òo›ùt{€"“Ts²–)‡hexText "ppÀhexText "pqÆ pˆà p•ÂÐx‡õphà "

QFile file("39059921.HA");

    if(!file.open(QIODevice::ReadOnly | QIODevice::Text))
       {
           return;
       }
      QTextStream stream(&file);
      while(!stream.atEnd())
      {
          QString line = stream.readLine();
          qDebug()<<"data"<<line;
      }

      file.close();

output:-I get the output like below
data"
"—¶GÐEÐk|‘s‰žÃ*¥òm[ˆ8êܳ$7¢,HYNܾlFTÛ/õêÃâlÂ¥Bóîä1©»0*¢Ïƒ©è~Êßl«Ê2<ˆWXˆ³8{Èà IÃ…@" 
data"&ÓûcVp„êp1¡Çø–ڐñT77”(/•´„ŸÎµ°©¯”9·|ÞmJ"5²ŒBÂ¡ó” ˜NWeB(¯e£÷•ˆ^Ó$Òo›ùt{€"“Ts²–)‡hexText "ppÀhexText "pqÆ pˆà p•ÂÐx‡õphà "

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How can I read the above and search for a particular address

[anda_skoa]

As you said, it is a binary file so don't treat it like a text file.

Open it without the text flag, seek to the position, read as many bytes as you want using QIODevice::read() (which QFile is a subclass of).

Cheers,
_

[anh5kor]

Actually its a Hex file which contain address and 16 bit hex data like below

00000020: FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF

I have tried reading as below

QFile file("abcdef.dat");
 
    if(!file.open(QIODevice::ReadOnly))
       {
           return;
       }
      QTextStream stream(&file);
      while(!stream.atEnd())
      {
          QString line = stream.readLine();
          QString hexText = QByteArray::fromHex(file.readLine());
          qDebug()<<"Text"<<line;
           qDebug()<<"hexText"<<hexText ;
      }
 
      file.close();

QFile file("abcdef.dat");

    if(!file.open(QIODevice::ReadOnly))
       {
           return;
       }
      QTextStream stream(&file);
      while(!stream.atEnd())
      {
          QString line = stream.readLine();
          QString hexText = QByteArray::fromHex(file.readLine());
          qDebug()<<"Text"<<line;
           qDebug()<<"hexText"<<hexText ;
      }

      file.close();

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but still not able to read.
Please let me know can we parse or read the hex file as like other text file.

[anda_skoa]

Are you sure it is a text file that contains text that is hex codes?
Can a text editor open it?

Cheers,
_

[anh5kor]

The file I can open only with Hex view Tool.
It can not be open with normal notepad or notepad++. If you try it will show some junk character
Its not a text file.

[anda_skoa]

Then why do you keep treating it like a text file?

If a text editor can't read it, why do you expect QTextStream to be able to?

Are you aware that not all byte sequences can be interpreted as text?

Cheers,
_

[ChrisW67]

There is a common inability to tell the difference between the human-readable representation of a set of bytes and the actual bytes at play here. This leads to the incorrect notion that the hexadecimal representation == the actual bytes. Once your brain is there it seems logical that fromHex() would be needed.

As you have already pointed out, this is what the OP wants to read a few bytes from the middle of the file:

QFile file("abcdef.dat");
if(file.open(QIODevice::ReadOnly)) {
  if (file.seek(100)) {
    QByteArray bytes = file.read(6); 
    // do something with bytes
  }
  file.close();
}

QFile file("abcdef.dat");
if(file.open(QIODevice::ReadOnly)) {
  if (file.seek(100)) {
    QByteArray bytes = file.read(6); 
    // do something with bytes
  }
  file.close();
}

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