I would have thought that declaring variables over and over would be less efficient than declaring them once at the start - that was my reasoning for declaring them before the loop, anyways...
Not only 'premature optimization is the root of all evil'; not only such a microoptimization is completely meaningless; but it's actually the other way around... declaring variables inside a loop is quite a bit faster. I guess due to Perl's own optimizations... 
use strict;
use warnings;

use Benchmark qw( cmpthese );

my @strings = qw(
  USERID1|2215|Jones|
  USERID1|1000|Jones|
  USERID3|1495|Dole|
  USERID2|2500|Francis|
  USERID2|1500|Francis|
);

cmpthese(
    1_000_000,
    {
        outside => sub {
            my ( $x, $y, $z );
            for (@strings) {
                ( $x, $y, $z ) = split /\|/;
            }
        },
        inside => sub {
            for (@strings) {
                my ( $x, $y, $z ) = split /\|/;
            }
        }
    }
);

[download]
result: 
            Rate outside  inside
outside 109890/s      --    -38%
inside  176678/s     61%      --

[download]

In reply to Re^3: Best way to store/sum multiple-field records? by Anonymous Monk
in thread Best way to store/sum multiple-field records? by bobdabuilda

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