Re: How do I remove whitespace at the beginning or end of my string?

[trizen]

Remove spaces at the beginning and end of your string. The fastest way, so far.

my $l = length($string);
$string = reverse unpack("A$l",reverse unpack("A$l",$string));

              Rate  two-s///     split m-capture    unpack s-with-\G
two-s///  239349/s        --       -6%      -38%      -40%      -41%
split     255782/s        7%        --      -33%      -36%      -37%
m-capture 384362/s       61%       50%        --       -4%       -5%
unpack    399865/s       67%       56%        4%        --       -1%

[jwkrahn]

No need for the string interpolation:

$string = reverse unpack( 'A*', reverse unpack( 'A*', $string ) );

[Tux]

It probably also depends on what perl you use, but I'm amazed by the unpack speed. Here's perl-5.14.2 bench:

use Benchmark "cmpthese";
use Regexp::Common "whitespace";

my $f = "   this is a string with  spaces  to    remove      ";
cmpthese (-3, {
    "Regexp-Common" => sub { my $g = $f; $g =~ s/$RE{ws}{crop}//g; },
    "two-s///"      => sub { my $g = $f; $g =~ s/^\s+//; $g =~ s/\s+$/
+/; },
    "one-s///"      => sub { my $g = $f; $g =~ s/^\s+|\s+$//g; },
    "s-capture"     => sub { my $g = $f; $g =~ s/^\s*(.*?)\s*$/$1/; },
    "s-capture2"    => sub { my $g = $f; $g =~ s/^\s*(\S+(?:\s+\S+)*)?
+\s*$/$1/; },
    "m-capture"     => sub { my $g = $f; ($g) = ($g =~ m/(\S+(?:\s+\S+
+)*)/); },
    "unpack"        => sub { my $g = $f; $g = reverse unpack "A*", rev
+erse unpack "A*", $g; },
    });

And the runs ...

5.15.5:

                Rate  one-s/// s-capture s-capture2 m-capture two-s///
+    unpack
one-s///    146152/s        --      -30%       -50%      -67%     -78%
+      -88%
s-capture   208100/s       42%        --       -30%      -53%     -69%
+      -83%
s-capture2  295196/s      102%       42%         --      -34%     -56%
+      -76%
m-capture   446788/s      206%      115%        51%        --     -34%
+      -64%
two-s///    673459/s      361%      224%       128%       51%       --
+      -46%
unpack     1239336/s      748%      496%       320%      177%      84%
+        --

5.14.2:

                Rate  one-s/// s-capture s-capture2 m-capture two-s///
+    unpack
one-s///    137451/s        --      -28%       -55%      -67%     -80%
+      -88%
s-capture   191603/s       39%        --       -38%      -53%     -72%
+      -84%
s-capture2  306586/s      123%       60%         --      -25%     -56%
+      -74%
m-capture   410529/s      199%      114%        34%        --     -41%
+      -65%
two-s///    692258/s      404%      261%       126%       69%       --
+      -41%
unpack     1172943/s      753%      512%       283%      186%      69%
+        --

5.14.1 (production perl with Rexexp::Common):

                   Rate Regexp-Common one-s/// s-capture s-capture2 m-
+capture two-s/// unpack
Regexp-Common   35655/s            --     -79%      -87%       -91%   
+   -94%     -96%   -97%
one-s///       171398/s          381%       --      -36%       -54%   
+   -69%     -79%   -88%
s-capture      268800/s          654%      57%        --       -29%   
+   -52%     -67%   -81%
s-capture2     376317/s          955%     120%       40%         --   
+   -32%     -53%   -74%
m-capture      556706/s         1461%     225%      107%        48%   
+     --     -31%   -61%
two-s///       808968/s         2169%     372%      201%       115%   
+    45%       --   -43%
unpack        1424354/s         3895%     731%      430%       278%   
+   156%      76%     --

5.12.4:

                Rate  one-s/// s-capture s-capture2 m-capture two-s///
+    unpack
one-s///    136992/s        --      -32%       -52%      -69%     -80%
+      -88%
s-capture   200658/s       46%        --       -30%      -54%     -71%
+      -82%
s-capture2  288356/s      110%       44%         --      -34%     -58%
+      -75%
m-capture   437898/s      220%      118%        52%        --     -37%
+      -62%
two-s///    694505/s      407%      246%       141%       59%       --
+      -39%
unpack     1143892/s      735%      470%       297%      161%      65%
+        --

5.10.1:

                Rate  one-s/// s-capture s-capture2 m-capture two-s///
+    unpack
one-s///    154239/s        --      -31%       -53%      -69%     -79%
+      -88%
s-capture   221974/s       44%        --       -32%      -55%     -70%
+      -83%
s-capture2  325661/s      111%       47%         --      -34%     -56%
+      -75%
m-capture   490550/s      218%      121%        51%        --     -34%
+      -62%
two-s///    740666/s      380%      234%       127%       51%       --
+      -42%
unpack     1278065/s      729%      476%       292%      161%      73%
+        --

5.8.9:

                Rate s-capture  one-s/// s-capture2 m-capture two-s///
+    unpack
s-capture   230743/s        --      -12%       -29%      -50%     -76%
+      -83%
one-s///    262166/s       14%        --       -19%      -43%     -73%
+      -81%
s-capture2  323587/s       40%       23%         --      -30%     -67%
+      -76%
m-capture   463883/s      101%       77%        43%        --     -53%
+      -66%
two-s///    977938/s      324%      273%       202%      111%       --
+      -28%
unpack     1354222/s      487%      417%       319%      192%      38%
+        --

5.6.2:

                Rate s-capture  one-s/// s-capture2 m-capture two-s///
+    unpack
s-capture   331911/s        --      -11%       -28%      -50%     -78%
+      -79%
one-s///    372325/s       12%        --       -19%      -44%     -75%
+      -76%
s-capture2  462448/s       39%       24%         --      -30%     -69%
+      -71%
m-capture   664093/s      100%       78%        44%        --     -56%
+      -58%
two-s///   1503714/s      353%      304%       225%      126%       --
+       -5%
unpack     1574832/s      374%      323%       241%      137%       5%
+        --

[Anonymous Monk]

Yup, unpack is packed chock full of speedy goodness, but as you probably know, it only handles " \r\f\t\n", won't handle the unicode whitespace like

#~ my $f = "  \x{000B}  vertical tab not removed   \x{000B}  ";
my $f = "  \x{00A0}  no-break space not removed   \x{00A0}  ";