FireBird34 has asked for the wisdom of the Perl Monks concerning the following question:

I need to strip all non-numeric characters within a scalar. I can do it with the output being stored in an array, but that's about it. Any ideas? This is the code I had: 
$scalar = "a1b2";
@array = split(/\D/,$scalar);
print @array;

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Also, talking with someone else (PHP they use), and they commented about using regex when doing what I need. Can someone enlighten me on using this to strip the non-numeric values? Thanks.

Replies are listed 'Best First'.
Re: Strip non-numeric
by ihb (Deacon) on Jan 13, 2003 at 22:55 UTC
    Sure, you can use a substitution:   s/\D//g; # global or you can use a special transliteration:   tr/0-9//cd; # complement, delete A more elaborate description is found in the perlop document.

    I must here point out that s/// and tr/// are two totally different operators! As said, they're documented in perlop.

    Other documents you might want to read are the perlre* documents. All perldocs are listed in the document "perl" (perldoc perl).

    Hope I've helped,
    ihb
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      Thanks all -- got it :-) I ended up using: 
      $scalar = "a1b2";
$scalar =~ s/\D//g;
print $scalar;

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      Also, I'll take a look at the perl documents on the s/// tr/// differences. Thanks.
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        You should consider using s/\D+//g, as that's often a lot faster than s/\D//g. Here's a benchmark: 
        #!/usr/bin/perl

use strict;
use warnings;

use Benchmark;

my @sizes = (10, 25, 50, 100, 250, 500, 1000);
my @chars = ('A' .. 'Z', 'a' .. 'z', 0 .. 9);

our @d = map {join "" => map {$chars [rand @chars]} 1 .. $_} @sizes;

map {
    Benchmark::cmpthese timethese (-2 => {
        "simple_$sizes[$_]"   => '$_ = $::d[' . $_ . ']; s/\D//g;',
        "multiple_$sizes[$_]" => '$_ = $::d[' . $_ . ']; s/\D+//g;'
    }, 'none');
} 0 .. $#sizes
__END__
                Rate   simple_10 multiple_10
simple_10   196495/s          --        -15%
multiple_10 231225/s         18%          --
                Rate   simple_25 multiple_25
simple_25    89788/s          --        -50%
multiple_25 180650/s        101%          --
                Rate   simple_50 multiple_50
simple_50    47507/s          --        -64%
multiple_50 130727/s        175%          --
                 Rate   simple_100 multiple_100
simple_100    23206/s           --         -77%
multiple_100 103096/s         344%           --
                Rate   simple_250 multiple_250
simple_250   10488/s           --         -71%
multiple_250 36407/s         247%           --
                Rate   simple_500 multiple_500
simple_500    5046/s           --         -75%
multiple_500 20382/s         304%           --
                 Rate   simple_1000 multiple_1000
simple_1000    2528/s            --          -76%
multiple_1000 10549/s          317%            --

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        Abigail

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Re: Strip non-numeric
by krujos (Curate) on Jan 13, 2003 at 22:50 UTC

    Try this  $var =~ s/\D//g; This (untested) code will remove all non-numeric characters from the string.

    Josh
    Update: I fixed my type where I left the g off the regexp. Sorry
    Update:2 I also fixed the /// problem that tall_man pointed out. Thanks.
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      There's one extra "/" at the end, and no "g" flag so only one would be removed. You need: 
      $var =~ s/\D//g;

      [download]
      Update: The "g" was just fixed in the message I replied to, but not the extra "/"
      Update 2:Now all the problems are fixed. :)
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Re: Strip non-numeric
by rbc (Curate) on Jan 13, 2003 at 22:52 UTC
    try ... 
    $scalar = "a1b2";
$scalar =~ s/\D//g;
print "$scalar\n";

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