http://www.perlmonks.org?node_id=1026027


in reply to Re^5: Out of Memory
in thread Out of Memory

Ah that makes sense, I was wondering if it would not replace if both were the same.

how does

++$n while $s=~ m[ab]g;;

differ in execution from

while($_=~s\0g) {count++}

Thanks for sharing

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Re^7: Out of Memory
by BrowserUk (Patriarch) on Mar 28, 2013 at 19:55 UTC
    how does ... differ in execution from ...

    Hm. "in execution"?

    1. The result -- the count -- is the same.
    2. The runtime is less than half:
      $s = 'ab'x 10e6;;

cmpthese -1, {
    a => q[ 
        my $n = 0; 
        while( $s =~ m[ab]g ){
            $n++
        };
    ],
    b=>q[
        my $n = 0; 
        ++$n while $s =~ m[ab]g;
    ],
};;

  s/iter    a    b
a   2.31   -- -37%
b   1.45  59%   --

      [download]
    3. It is easier to read.

    Don't use post increment if you aren't using the pre-increment value. Don't create scopes you don't need.

    Or, get into the habit of not doing anything you don't need to.

    With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'
    Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
    "Science is about questioning the status quo. Questioning authority".
    In the absence of evidence, opinion is indistinguishable from prejudice.
[reply]
[d/l]
      Thank you for the very thorough explanation and proof.

      If you don't know where you're going, it doesn't matter when you get there.
[reply]

In Section Seekers of Perl Wisdom