While refactoring some code I got to wondering about 'what is the fastest way to remove the first character in a string?' So I cobbled together some code to find out. I had been using s/.//; but I am admittedly prone to regex abuse. I found the results to be a little surprising and wondered if anyone else had different entries for the putative horse race? 
#!/perl/bin/perl
#
# bench.pl --
use strict;
use warnings;
use diagnostics;
use Benchmark qw(:all);

sub caseone {
    $_ = '|0|0|0|0|0|0|';
    s/.//;
}

sub casetwo {
    $_ = '|0|0|0|0|0|0|';
    substr($_,0,1) = '';
}

sub casethree {
    $_ = '|0|0|0|0|0|0|';
    $_ = reverse $_;
    chop;
    $_ = reverse $_;
}

sub casefour {
    $_ = '|0|0|0|0|0|0|';
    $_ = substr($_,1);
}

cmpthese(-5,{
    'caseone' => 'caseone',
    'casetwo' => 'casetwo',
    'casethree' => 'casethree',
    'casefour' => 'casefour',
});

[download]
And the results look like: 
              Rate   caseone casethree   casetwo  casefour
caseone   293156/s        --      -12%      -21%      -32%
casethree 331364/s       13%        --      -10%      -23%
casetwo   369954/s       26%       12%        --      -14%
casefour  430979/s       47%       30%       16%        --

[download]

--hsm

"Never try to teach a pig to sing...it wastes your time and it annoys the pig."

In reply to Ways to delete start of string by hsmyers

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