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Re^2: Skip a row of csv file.

by TomDLux (Vicar)
on May 04, 2012 at 18:02 UTC ( #968961=note: print w/ replies, xml ) Need Help??


in reply to Re: Skip a row of csv file.
in thread Skip a row of csv file.

While many people do use regular expressions, I think that's like using an M16 to crack walnuts.

R.E. are the appropriate solution when you have variable components, but testing a constant string is precisely what 'eq' is for.

As Occam said: Entia non sunt multiplicanda praeter necessitatem.


Comment on Re^2: Skip a row of csv file.
Re^3: Skip a row of csv file.
by aaron_baugher (Deacon) on May 04, 2012 at 23:35 UTC

    You make a good point, but I found myself wondering how the combination of substr, length, and eq would compare to a single anchored regex, so I did a benchmark. I'm convinced!

    bannor:~/work/perl/monks$ cat 968838.pl #!/usr/bin/env perl use Modern::Perl; use Benchmark qw(:all); my $str = 'A.SERIAL_NUMBER||abcdefghijklmnopqrstuvwxyz'; my $ss = 'A.SERIAL_NUMBER||'; my $yay; cmpthese( 10_000_000, { 'substr' => sub { if(substr($str,0,length($ss)) eq $ss ){ $yay = 1; } }, 'regex' => sub { if( $str =~ /^\Q$ss\E/ ){ $yay = 1; } }, }); bannor:~/work/perl/monks$ perl 968838.pl Rate regex substr regex 1312336/s -- -65% substr 3802281/s 190% --

    Aaron B.
    My Woefully Neglected Blog, where I occasionally mention Perl.

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