How to detect a string in torrent file?

[poncho]

Hi,

I'm working on a BEncoding class in VB.NET. It works great but actually byte strings are read as byte arrays because there can be stored binary data (files hashes for example).

How can I recognize a text string?

[jewelisheaven]

You can't? A basic check would be to see if it contains NULLs but even that isn't a good test... Ultima mentions this in the BFE thread http://forum.utorrent.com/viewtopic.php?pid=329008#p329008 You may want to pipe in there and ask.

[poncho]

OK, to differentiate between text strings and byte strings I do this:

Byte strings are getting a NULL (0) at first position. Now I can easily differ between text and binary data.

[Ultima]

I'm not really seeing how that helps you to determine what's text and what's simply binary data... O_o

[poncho]

It's only for debugging. The program doesn't need it but it's easier for me because I can see what's in a variable as text and not as byte array.

[Burningmace]

Dunno if you're still working on this, but here's some pointers for you:

Readable text has a whole range of characters - 0x0A and 0x0D for Line Feed and Carriage Return characters (newlines) and 0x20 (decimal 32) to 0x7E (decimal 126) for printable ASCII characters. So, if you want some code here it is:

Function IsReadableText(data As Byte()) As Boolean
    For i As UInt64 = 0 To data.Length - 1
        If Not ((data(i) >= 32 And data(i) <= 126) Or data(i) = 10 Or data(i) = 13) Then
            Return False
        End If
    Next
    Return True
End Function

It's reasonably good performance too, as the instant a "non-readable" character is found it returns false.