Perl: the Markov chain saw PerlMonks

### Re^2: Array Filter and Lookahead

by AnomalousMonk (Canon)
 on Nov 20, 2012 at 19:51 UTC ( #1004783=note: print w/replies, xml ) Need Help??

The solutions you propose have various problems:

• handling a number like 3.0, of which daugh016 seems to want to capture only the integer portion;
• handling 0;
• and the problem of having capture variables undefined if a match fails (or else having the value of these variables persist from a previous match).

Here is a possible solution avoiding those problems:

```>perl -wMstrict -le
"my @test = (
'text text text 1 text',
'1 text text text 2 text 3 ',
'text 1 text text 2 text',
'text text text 1 text 2 3.0',
'1 2 3 4 5 6 7 8 9 10 11',
'text 0',  'text 3.1',
'text text text text',
);
;;
'Zonk' =~ m{ (\w+) }xms;
;;
my @filtered = map {/(\d+)(?:\.0*)?\D*\$/; \$1} @test;
printf qq{'\$_' } for @filtered;
print qq{\n};
;;
@filtered = map {/(\d+(?:\.\d*)?)\D*\$/; 0 + \$1 || ''} @test;
printf qq{'\$_' } for @filtered;
print qq{\n};
;;
@filtered =
map { m{ (\d+) (?: [.] \d*)? \D* \z }xms ? \$1 : '' }
@test
;
printf qq{'\$_' } for @filtered;
print qq{\n};
"
'1' '3' '2' '3' '11' '0' '1' 'Zonk'

Argument "Zonk" isn't numeric in addition (+) at -e line 1.
'1' '3' '2' '3' '11' '' '3.1' ''

'1' '3' '2' '3' '11' '0' '3' ''

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