Regex ignore if empty - php

Question

I have two conditions in my regex (regex used on php)
(BIOLOGIQUES\s+(\d+)\s+(\d+)\s+\/\s+(\d+))|(Dossier N.\s+:\s+(\d+)\s+(\d+)\s+\/\s+(\d+))
When I test the 1st condition with the following I get 4 match groups 1 2 3 and 4
BIOLOGIQUES 47 131002 / 4302
Please see the 1st condition here http://www.rubular.com/r/a6zQS8Wth6
But when I test with the second condition the groups match are 5 6 7 and 8
Dossier N° : 47 131002 / 4302
The second condition here : http://www.rubular.com/r/eYzBJq1rIW
Is there a way to always have 1 2 3 and 4 match groups in the second condition too?

Answer 1

Since the parts of both regexps that match the numbers are the same, you can do the alternation just for the beginning, instead of around the entire regexp:
preg_match('/((?:BIOLOGIQUES|Dossier N.\s+:)\s+(\d+)\s+(\d+)\s+\/\s+(\d+))/u', $content, $match);
Use the u modifier to match UTF-8 characters correctly.

Answer 2

I assume your regex is compressed. If the dot is meant to abbrev. the middle initial it should be escaped. The suggestion below factors out like Barmar's does. If you don't want to capture the different names, remove the parenthesis from them.
Sorry, it looks like you intend it to be a dot metachar. Just remove the \ from it.
# (?:(BIOLOGIQUES)|(Dossier\ N\.\s+:))\s+((\d+)\s+(\d+)\s+\/\s+(\d+))
(?:
( BIOLOGIQUES ) # (1)
| ( Dossier\ N \. \s+ : ) # (2)
)
\s+
( # (3 start)
( \d+ ) # (4)
\s+
( \d+ ) # (5)
\s+ \/ \s+
( \d+ ) # (6)
) # (3 end)
Edit, the regex should be factored, but if it gets too different, a way to re-use the same capture groups is to use Branch Reset.
Here is your original code with some annotations using branch reset.
(?|(BIOLOGIQUES\s+(\d+)\s+(\d+)\s+\/\s+(\d+))|(Dossier\ N.\s+:\s+(\d+)\s+(\d+)\s+\/\s+(\d+)))
(?|
br 1 ( # (1 start)
BIOLOGIQUES \s+
2 ( \d+ ) # (2)
\s+
3 ( \d+ ) # (3)
\s+ \/ \s+
4 ( \d+ ) # (4)
1 ) # (1 end)
|
br 1 ( # (1 start)
Dossier\ N . \s+ : \s+
2 ( \d+ ) # (2)
\s+
3 ( \d+ ) # (3)
\s+ \/ \s+
4 ( \d+ ) # (4)
1 ) # (1 end)
)
Or, you could factor it AND use branch reset.
# (?|(BIOLOGIQUES\s+)|(Dossier\ N.\s+:\s+))(?:(\d+)\s+(\d+)\s+\/\s+(\d+))
(?|
br 1 ( BIOLOGIQUES \s+ ) # (1)
|
br 1 ( Dossier\ N . \s+ : \s+ ) # (1)
)
(?:
2 ( \d+ ) # (2)
\s+
3 ( \d+ ) # (3)
\s+ \/ \s+
4 ( \d+ ) # (4)
)