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Re: chopping lots of characters

by hmerrill (Friar)
on Jun 24, 2004 at 12:12 UTC ( [id://369306]=note: print w/replies, xml ) Need Help??


in reply to chopping lots of characters

Yeah you can do that by calling chop 4 times, but that's 4 function calls. Without actually checking performance on this I would think(?) that one call to substring would be faster, but... 
   $string = substr($string, 0, -4);

[download]
that will give you $string containing all but the last 4 characters of what it started with.

HTH.

Replies are listed 'Best First'.
Re: chopping lots of characters
by Abigail-II (Bishop) on Jun 24, 2004 at 12:38 UTC
    A quicky test shows that 3-arg substr is faster than chop, but a 4-arg substr is even faster - and that's to be expected because it saves a copy. Differences aren't dramatic though. 
    #!/usr/bin/perl
                   
use strict;
use warnings;   

use Benchmark qw /cmpthese/;
                
chomp (our @strings = <DATA>);
                    
cmpthese -5 => {
    chop    => 'my @copy = @strings;
                foreach my $str (@copy) {
                    chop $str;
                    chop $str;
                    chop $str;
                    chop $str;
                }',
    substr3 => 'my @copy = @strings;
                foreach my $str (@copy) {
                    $str = substr $str => 0, -4;
                }',
    substr4 => 'my @copy = @strings;
                foreach my $str (@copy) {
                    substr $str => -4, 4 => "";
                }',
};
                
__DATA__
asdfjas;dfjas;dfjas;dkfjasdfasdf
asd
    
sdfajsd;flaks



            Rate    chop substr3 substr4
chop    152166/s      --    -11%    -14%
substr3 170187/s     12%      --     -4%
substr4 176800/s     16%      4%      --

    [download]
[reply]
[d/l]

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