I think the split() solution is more efficient than the regex solution.

Tested with Perl 5.8.8 (ActiveState on WinXP)

#!/usr/bin/perl
use strict;
use warnings;
use Benchmark qw( cmpthese );

my $str = ( ('X'x15) . ',' ) x 3;

cmpthese(
    -1,
    {
        # using regex
        's///' => sub {
            my ( $first ) = $str =~ m/(.*?),/;
        },
        # using split without limit
        'split_unl' => sub {
            my ( $first ) = split( m/,/, $str );
        },
        # using split with limit
        'split_lim' => sub {
            my ( $first ) = split( m/,/, $str, 2 );
        },
        # using split with limit and slice for scalar assignment
        'split_lim_sca' => sub {
            my $first = ( split( m/,/, $str, 2 ) )[0];
        },
    }
)

[download]

my result:

                  Rate          s///     split_lim     split_unl split
+_lim_sca
s///          577066/s            --          -13%          -13%      
+    -15%
split_lim     663032/s           15%            --           -0%      
+     -2%
split_unl     663629/s           15%            0%            --      
+     -2%
split_lim_sca 679348/s           18%            2%            2%      
+      --

[download]

Or did I miss something?

In reply to Re^2: Regex to take an ip address before a comma by linuxer
in thread Regex to take an ip address before a comma by Anonymous Monk

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