Help with parsing a string

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

I have an executable that outputs to STDERR and STDOUT the following:

00 0A EF 85 BA 8F AA BC
[download]

(and it keeps going for a while until an end of line character)

I built a perl script I want to pipe this output into. So to run it I would do the

Extractor.exe |& output.pl

#!/usr/bin/perl
# Name: output.pl
#
while (<>)
  next if !~ m/([0-9a-f])([0-9a-f]) ([0-9a-f])([0-9a-f])/;
  $a = sprintf("%s%s%s%s",$1,$2,$3,$4);
}
[download]

This is so ugly! And to do this for my whole "line" of output, I have to do like fifty captures. I was hoping someone had a more efficient way of doing this. Help please. Thanks, S

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Re: Help with parsing a string by moritz (Cardinal) on Jul 22, 2008 at 21:05 UTC
It seems that you're just trying to remove all whitespaces: `s/\s+//g;` [download] Of course that doesn't verify your data, so you could use split instead (untested): `OUTER: while (<>){ chomp; my @items = split m/\s/; for my $i (@items) { last OUTER unless $i =~ m/^[a-f\d]{2}$/; } print join '', @items; }` [download]	[reply] [d/l] [select]
Re^2: Help with parsing a string by pc88mxer (Vicar) on Jul 22, 2008 at 21:31 UTC
If you lines contain other text besides the hex numbers, you can restrict the space removal to just between the hex numbers with: `$line =~ s{\b([a-f\d]{2})\s+(?=[a-f\d]{2}\b)}{$1}gi;` [download]	[reply] [d/l]
Re: Help with parsing a string by GrandFather (Saint) on Jul 22, 2008 at 21:38 UTC
Well, you could: `use strict; use warnings; my $byte = qr/([0-9a-f]{2})/i; while (<DATA>) { my $line = join '', /\b$byte\b/g; next unless length $line; print "$line\n"; } __DATA__ 00 0A EF 85 BA 8F AA BC Wibble 00 0A EF 85 BA 8F AA BC` [download] Prints: `000AEF85BA8FAABC 000AEF85BA8FAABC` [download] Perl is environmentally friendly - it saves trees	[reply] [d/l] [select]
Re: Help with parsing a string by jethro (Monsignor) on Jul 22, 2008 at 21:14 UTC
Well, if you want to print those 4 chars, just do `print $1,$2,$3,$4;` [download] Even better, if all you want is just to eliminate spaces in that string, do `s/ //g; print;` [download] If that is not what you want, you have to be more specific.	[reply] [d/l] [select]
Re: Help with parsing a string by toolic (Bishop) on Jul 23, 2008 at 01:09 UTC
Yet another way to represent a hexadecimal digit is to use the POSIX character class (see perlre): `[[:xdigit:]]` [download]	[reply] [d/l]