comment on

Nice, never occurred to me to use join split for that task.

~~Though using s/// seems to be noticeable faster, at least if not used with an alternating regex:~~

use strict;
use warnings;

use Benchmark qw(cmpthese);

my $short = q(     a   b   c    );
my $long = join('x', map {' ' x (int(rand(20))+1)} 1 .. 100);

my %func = (
    triple_s => <<'EOFUNC',
        sub {
            my $str = $_;
            $str =~ s/^\s*//;
            $str =~ s/\s*$//;
            $str =~ s/\s+/ /g;
            $str;
        }
EOFUNC
    double_s => <<'EOFUNC',
        sub {
            my $str = $_;
            $str =~ s/^\s*|\s*$//;
            $str =~ s/\s+/ /g;
            $str;
        }
EOFUNC
    join_split => <<'EOFUNC',
        sub {
            my $str = $_;
            join ' ', split ' ', $str;
        }
EOFUNC
);

sub make {
    my ($str, $f) = @_;
    ($f = $func{$f}) =~ s/_/$str/;
    eval $f;
}

print "\nShort string:\n";
cmpthese(-1, {
        'triple-s' => make(qw(short triple_s)),
        'double-s' => make(qw(short double_s)),
        'join-split' => make(qw(short join_split)),
    });

print "\nLong string:\n";
cmpthese(-1, {
        'triple-s' => make(qw(long triple_s)),
        'double-s' => make(qw(long double_s)),
        'join-split' => make(qw(long join_split)),
    });
[download]

giving:

Short string:
               Rate   triple-s join-split   double-s
triple-s   305867/s         --       -31%       -37%
join-split 441107/s        44%         --        -9%
double-s   482473/s        58%         9%         --

Long string:
              Rate   triple-s join-split   double-s
triple-s    4775/s         --       -69%       -86%
join-split 15251/s       219%         --       -55%
double-s   33822/s       608%       122%         --
[download]

Update, in reaction to ikegami's reply:

My above code is seriously flawed. Not only the unprovoked change from + to *, but moreso in forgetting the mandatory g modifier in the regex with alternation which should trim the start and the end of the argument string!

Should have told me something, that the version with the worse reputation scored best!

So here comes my corrected and expanded try:

use strict;
use warnings;

use Benchmark qw(cmpthese);

my $short = q(     a   b   c    );
my $long = join('x', map {' ' x (int(rand(20))+1)} 1 .. 100);

my %func = (
    triple_s => <<'EOFUNC',
        sub {
            my $str = $_;
            $str =~ s/^\s*//;
            $str =~ s/\s*$//;
            $str =~ s/\s+/ /g;
            $str;
        }
EOFUNC
    triple_sp => <<'EOFUNC',
        sub {
            my $str = $_;
            $str =~ s/^\s+//;
            $str =~ s/\s+$//;
            $str =~ s/\s+/ /g;
            $str;
        }
EOFUNC
    triple_sp_r => <<'EOFUNC',
        sub {
            my $str = $_;
            $str =~ s/\s+/ /g;
            $str =~ s/^\s+//;
            $str =~ s/\s+$//;
            $str;
        }
EOFUNC
    double_s => <<'EOFUNC',
        sub {
            my $str = $_;
            $str =~ s/^\s*|\s*$//g;
            $str =~ s/\s+/ /g;
            $str;
        }
EOFUNC
    double_sp => <<'EOFUNC',
        sub {
            my $str = $_;
            $str =~ s/^\s+|\s+$//g;
            $str =~ s/\s+/ /g;
            $str;
        }
EOFUNC
    double_sp_r => <<'EOFUNC',
        sub {
            my $str = $_;
            $str =~ s/\s+/ /g;
            $str =~ s/^\s+|\s+$//g;
            $str;
        }
EOFUNC
    join_split => <<'EOFUNC',
        sub {
            my $str = $_;
            join ' ', split ' ', $str;
        }
EOFUNC
);

sub make {
    my ($str, $f) = @_;
    ($f = $func{$f}) =~ s/_/$str/;
    eval $f;
}

print "\nShort string:\n";
cmpthese(-5, {
        '3-s' => make(qw(short triple_s)),
        '2-s' => make(qw(short double_s)),
        '3-sp' => make(qw(short triple_sp)),
        '2-sp' => make(qw(short double_sp)),
        '3-sp_r' => make(qw(short triple_sp_r)),
        '2-sp_r' => make(qw(short double_sp_r)),
        'j-split' => make(qw(short join_split)),
    });

print "\nLong string:\n";
cmpthese(-5, {
        '3-s' => make(qw(long triple_s)),
        '2-s' => make(qw(long double_s)),
        '3-sp' => make(qw(long triple_sp)),
        '2-sp' => make(qw(long double_sp)),
        '3-sp_r' => make(qw(long triple_sp_r)),
        '2-sp_r' => make(qw(long double_sp_r)),
        'j-split' => make(qw(long join_split)),
    });
[download]

Which gives on this machine:

Short string:
            Rate     2-s    2-sp  2-sp_r     3-s  3-sp_r    3-sp j-spl
+it
2-s     114468/s      --    -14%    -26%    -28%    -42%    -47%    -4
+7%
2-sp    132675/s     16%      --    -14%    -17%    -33%    -38%    -3
+8%
2-sp_r  155014/s     35%     17%      --     -3%    -21%    -28%    -2
+8%
3-s     159352/s     39%     20%      3%      --    -19%    -26%    -2
+6%
3-sp_r  196609/s     72%     48%     27%     23%      --     -8%     -
+9%
3-sp    214344/s     87%     62%     38%     35%      9%      --     -
+0%
j-split 214880/s     88%     62%     39%     35%      9%      0%      
+--

Long string:
           Rate     2-s    2-sp     3-s j-split  2-sp_r    3-sp  3-sp_
+r
2-s      1961/s      --     -3%    -37%    -76%    -77%    -83%    -85
+%
2-sp     2029/s      3%      --    -34%    -76%    -76%    -83%    -85
+%
3-s      3092/s     58%     52%      --    -63%    -63%    -74%    -77
+%
j-split  8343/s    325%    311%    170%      --     -1%    -29%    -38
+%
2-sp_r   8443/s    331%    316%    173%      1%      --    -28%    -38
+%
3-sp    11694/s    496%    476%    278%     40%     39%      --    -13
+%
3-sp_r  13512/s    589%    566%    337%     62%     60%     16%      -
+-
[download]

In reply to Re: removing the white spaces by pKai
in thread removing the white spaces by Anonymous Monk

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