preg_replace() returns empty string

Question

preg_replace() is returning an empty string for the following line of code. The aim is to replace anything that's not a number with a hyphen. Through an online tester I believe the regex catches the right things, but for some reason this line is always returning an empty string.

preg_last_error() returns no error. Any suggestions?

$subRef = preg_replace("/[^(\d)]/g", "-", $subRef);

Enable `error_reporting(E_ALL);`. It'll tell you what's wrong with your regex specifier. — mario, Aug 29 '13 at 15:34
possible duplicate of ["Unknown modifier 'g' in..." when using preg\_match in PHP?](http://stackoverflow.com/questions/3578671/unknown-modifier-g-in-when-using-preg-match-in-php) — mario, Aug 29 '13 at 15:36
Currently testing subRef with 9999-99.99, echoing before and after this line, so pretty sure the right value is going in. — Chris, Aug 29 '13 at 15:36
as @mario said enable error_reporting as you will be forever having unexplained problems developing with it disabled http://stackoverflow.com/questions/845021/how-to-get-useful-error-messages-in-php — Anigel, Aug 29 '13 at 15:40
@mario - That was my problem, thank you. I presume preg_replace won't accept the g modifier as it is global by default - if you'd like to post that as a full answer, I'll happily accept! — Chris, Aug 29 '13 at 15:46

score 9 · Accepted Answer · edited May 23 '17 at 10:27

9

For people finding this on Google, the issue was my g flag.

As I understand, PHP doesn't have a global flag, as the function you use decides if the regex is global or not.

Credit for this answer to Mario in the comments on the question.

edited May 23 '17 at 10:27

Community

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answered Sep 12 '13 at 16:27

Chris

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score 5 · Answer 2 · answered Aug 29 '13 at 15:37

5

Try

preg_replace('/\D/', '-', $subRef);

instead. \D is "not-a-digit"

php > $foo = 'abc123def';
php > echo preg_replace('/\D/', '-', $foo);
---123---

answered Aug 29 '13 at 15:37

Marc B

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Thanks, wasn't aware of the \D, and it's a much tidier way of doing what I'm doing. It was the g-modifier causing the problem though. Using this regardless however, Cheers! – Chris Aug 29 '13 at 15:48

preg_replace() returns empty string

2 Answers2