Re^2: out of two strings which occurs first in a text

Four bugs.

The g is an error.
You treat the contents of $first and $second as patterns.
if($1) doesn't work. $1 is not erased on a failed match.
if($1) doesn't work. $1 could be spaces or zeroes.

Fix:

my ($earliest) = $str =~ /(\Q$first\E|\Q$second\E)/;
print( "$earliest\n" ) if defined( $earliest );
[download]

Update: Added 4th bug.

Comment on Re^2: out of two strings which occurs first in a text Select or Download Code

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Re^3: out of two strings which occurs first in a text by jwkrahn (Abbot) on Sep 24, 2008 at 10:05 UTC
Add another possible bug. If, for example, `$first` contains `'pat'` and `$second` contains `'pattern'` then `$first` will always match first.	[reply] [d/l] [select]
Re^4: out of two strings which occurs first in a text by wol (Hermit) on Sep 24, 2008 at 13:35 UTC
True, but this is one of those cases where the bug is in the requirements as much as the implementation - what is the desired result in this case? -- .sig : File not found.	[reply]
Re^4: out of two strings which occurs first in a text by dec (Beadle) on Sep 24, 2008 at 13:39 UTC
That behaviour surprised me so I checked it out. You're right, but I would have expected the greediness of perls's regexp matching to favour the longer string. Interesting.	[reply]
Re^5: out of two strings which occurs first in a text by ikegami (Patriarch) on Sep 24, 2008 at 20:28 UTC
It's not a question of greediness. "pat" matched, so the alternation was successful. "pat" can't possible match any more than it has, so that's the end of the alternation. Elements of alternations are tried in turn. Greediness would factor in if you had /pat(?:tern)?/. If you wanted to get the longest first, sort the elements of the alternation. `my ($re) = map qr/$_/, join '\|', map quotemeta, sort { length($b) <=> length($a) } @words;` [download] Of course, that doesn't work for patterns that can match strings of various lengths.	[reply] [d/l]