Well here it is: Proof that you can really perform a task in multiple ways. I needed an efficient way to cut off trailing whitespace. I was pulling values from a database and the scalars all had trailing whitespace. I had mistakenly made the column type CHAR(10) when it should have been a VARCHAR. Let me just say that the details of the job make it alright to cut the whitespace instead of fixing the underlying problem

So I had three ideas (none original) to perform this task. Here is my benchmark script.


use Benchmark;
timethese (1000000, {
        'unpack' => q{  my $foo = "test    ";
                        $foo = unpack("A8",$foo); },
        'regex'  => q{  my $foo = "test    ";
                        $foo =~ s/\s+$//;},
        'xeger'  => q{  my $foo = reverse "test    ";
                        $foo =~ s/^\s+//;
                        $foo = reverse $foo;}
} );

[download]

The standard regex, the unpack function, and the reverse regex. I figured the reverse one maybe wouldn't apply because the is no .* in the match. But it is cool enough an idea to try out.

Here are my results:

Benchmark: timing 1000000 iterations of regex, unpack, xeger...
     regex:  6 wallclock secs ( 5.71 usr +  0.00 sys =  5.71 CPU) @ 17
+5131.35/s (n=1000000)
    unpack:  7 wallclock secs ( 5.91 usr +  0.00 sys =  5.91 CPU) @ 16
+9204.74/s (n=1000000)
     xeger:  9 wallclock secs ( 9.26 usr +  0.00 sys =  9.26 CPU) @ 10
+7991.36/s (n=1000000)

[download]

So it seems that the regex and the unpack are very close to the same time. Notice that this is for 1 million iterations. All methods are fast. So you can use various methods for this task!

Thank you, goodnight.

In reply to Removing Trailing Whitespace: Multiple ways. by DeaconBlues

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.