Re: Understanding regular expressions: why do I have to use map to clear up undefs in regex output?

[Marshall]

Another method is to use regex s/// to clean up string and then just use split.

#!/usr/bin/perl -w
use strict;
use Data::Dumper;

my $s = '1,2,3,4,"fine",,,"day","today",,,';

$s =~ s/['"]//g;   #no quotes

my @s = split(/,/,$s);

print Dumper \@s;
__END__
$VAR1 = [
          '1',
          '2',
          '3',
          '4',
          'fine',
          '',
          '',
          'day',
          'today'
        ];

Update: I personally prefer the {} syntax of grep. Example: to "get rid of the blank tokens above, just @s = grep {/\S/}@s;. If you want to get rid of some undef values: @s = grep{defined $_}@s. Perl grep is a filtering operation. Perl map is a transformation operation. Use grep when you just want a subset of the data and aren't changing it. Use map when you are transforming the data input into something else.