The first regular expression is quite neat. I came up with a similar - but quite ungainly - solution to the problem (see the code below). I assumed that my code, being a bit of a mess would be particularly slow and inefficient so being curious I compared the two solutions using some code borrowed from httptech. 
#!/usr/local/bin/perl

use Benchmark;

my $str = "the %0A quick %2b brown %63 fox  %63 jumped %24 over %7e th
+e %4f%45 lazy %25 dog";
 
timethese (500000, {
   'myway' => sub {
        $_ = $str;
        while (/%[0-9A-Fa-f]{2}/) {
            $_ = $&;
            /[0-9A-Fa-f]{2}/;
            $ob[0] = hex($&);
            $temp = pack("C*", @ob);
            $name =~ s/%[0-9A-Fa-f]{2}/$temp/;
            $_ = $name;
            }
        },
   'regexpway' => sub {
        $_ = $str;
        s/%([a-fA-F0-9]{2})/pack("C", hex($1))/eg;
        },
            }); 

Benchmark: timing 500000 iterations of myway, regexpway...
     myway: 23 wallclock secs (21.99 usr +  0.00 sys = 21.99 CPU)
 regexpway: 57 wallclock secs (57.58 usr +  0.00 sys = 57.58 CPU)

[download]
I was quite suprised that my messy solution appeared to be significantly faster than the reg exp.
Any ideas why this is?

In reply to RE: form parsing, hex, HTML formatting by muppetBoy
in thread form parsing, hex, HTML formatting by Anonymous Monk

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