#!/usr/bin/perl -w

use strict;
use Time::HiRes qw( gettimeofday tv_interval);

my @temp=("a_1","b_1","a_2","a_3","a_4","b_2","a_5","b_3","a_6","b_4");

my @startTime = gettimeofday;
for ( 1..10000 ) {
my (@a, @b) ;
foreach my $value (@temp) {
    push @a, $1 if ($value =~ /a_(.*)/) ;
    push @b, $1 if ($value =~ /b_(.*)/) ;
}
}

print "Time: ".tv_interval( \@startTime )."\n";

@temp = qw( a_1 b_1 a_2 a_3 a_4 b_2 a_5 b_3 a_6 b_4 );

@startTime = gettimeofday;

for ( 1..10000 ) {
my %values;
foreach (@temp) {
    /^([ab])_(.*)/ && do {
        push @{$values{$1}}, $2;
        next;
    };

    die "'$_' doesn't match the pattern of ^[ab]_.*\n";
}
}


print "Time: ".tv_interval( \@startTime )."\n";
@temp = qw( a_1 b_1 a_2 a_3 a_4 b_2 a_5 b_3 a_6 b_4 );

@startTime = gettimeofday;
for ( 1..10000 ) {
my (@a, @b);
foreach (@temp) {
  my $prefix = substr( $_, 0, 2 );

  if ( $prefix eq 'a_' ) {
    push @a, substr( $_, 2 );
  } elsif ( $prefix eq 'b_' ) {
    push @b, substr( $_, 2 );
  }
}
}

print "Time: ".tv_interval( \@startTime )."\n";


@startTime = gettimeofday;
for ( 1..10000 ) {
my( @a, @b );
my %arrays;
eval qq{\$arrays{ "$_" } = \\\@$_} for qw( a b );
for( @temp ) {
  die "Invalid prefix on element '$_'\n" unless /^([ab])_(.*)/;
  push @{ $arrays{ $1 } }, $2;
}
}
print "Time: ".tv_interval( \@startTime )."\n";


@startTime = gettimeofday;
for ( 1..10000 ) {
  my @a = map {/a_(.*)/ ? $1 : ()} @temp;
  my @b = map {/b_(.*)/ ? $1 : ()} @temp;
}
print "Time: ".tv_interval( \@startTime )."\n";

@startTime = gettimeofday;
for ( 1..10000 ) {
  my @a_arr = grep { s/^a_(.*)/$1/} @temp;
  my @b_arr = grep { s/^b_(.*)/$1/} @temp;
}
print "Time: ".tv_interval( \@startTime )."\n";

# GAVE ME substr outside of string at ./testme2.pl line 88.
#@startTime = gettimeofday;
#for ( 1..10000 ) {
#  my %parts;
#  push @{ $parts{ substr $_, 0, 1 }}, substr $_, 2
#  foreach @temp;
#}
#print "Time: ".tv_interval( \@startTime )."\n";


@startTime = gettimeofday;
for ( 1..10000 ) {
  my (@a, @b) ;
  m[^([ab])_(.*)$] and push @{$1 eq 'a' ? \@a : \@b}, $2 for @temp;
}
print "Time: ".tv_interval( \@startTime )."\n";

Output:
Time: 0.575739
Time: 0.717803
Time: 0.46604
Time: 1.731715
Time: 0.777471
Time: 0.462416
Time: 0.103439