Looking for regexp to convert hex numbers in text

jepri has asked for the wisdom of the Perl Monks concerning the following question:

I have a program that generates a text file interspersed with the unprintable characters turned into hex codes in the form [0xff]

I have been trying to write a one shot regexp that would trawl through the entire document and convert the hex codes back into the characters, but this code is the best I can come up with.

Can anyone see a better way to do it?

while ( my ( $hex ) = ($line =~ m/\[0x(..?)\]/)) {
    my $chr =  pack("h*", $hex);
    #print "$line \n Found hex value '$hex', equals char $chr\n";
    $line =~ s/\[0x$hex\]/$chr/;
}
[download]

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Jeremy
I didn't believe in evil until I dated it.

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Re: Looking for regexp to convert hex numbers in text by rob_au (Abbot) on Nov 06, 2001 at 18:11 UTC
From URI::Escape ... `s/%([0-9A-Fa-f]{2})/chr(hex($1))/eg` ... which can easily be adapted, thus ... `s/\[0x([\da-fA-F]{2})\]/chr(hex($1))/eg` Ooohhh, Rob no beer function well without!	[reply] [d/l] [select]
Re: Looking for regexp to convert hex numbers in text by busunsl (Vicar) on Nov 06, 2001 at 18:13 UTC
try: `$line =~ s/(\[0x(.{2})\])/chr($2)/eg;` [download]	[reply] [d/l]
Re: Re: Looking for regexp to convert hex numbers in text by Hofmator (Curate) on Nov 07, 2001 at 16:40 UTC
Two things: This doesn't work, you have to use `chr(hex($2))`otherwise the numbers are converted as integer values and not hex! You don't need two pairs of capturing parens, this is unnecessary extra work for the regex engine. So the correct solution is `s/\[0x([a-f0-9A-F]{1,2})\]/chr(hex($1))/eg;` -- Hofmator	[reply] [d/l] [select]
Re: Looking for regexp to convert hex numbers in text by Zaxo (Archbishop) on Nov 06, 2001 at 18:21 UTC
`s/(0x[0-9a-fA-F]+)/chr(oct($1))/ego;` After Compline, Zaxo	[reply] [d/l]
Re: Looking for regexp to convert hex numbers in text by staeryatz (Monk) on Nov 07, 2001 at 02:08 UTC
From where I learned Perl, you can do this: `$value =~ s/%([a-fA-F0-9][a-fA-F0-9])/pack("C", hex($1))/eg;` [download] You can use pack "C" here, to convert to unsigned chars. I use this as a part of URL decoding in CGI scripts. This packs a pair of Hex characters into an unsigned character, using the substitute function.	[reply] [d/l]