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
– mario, Commented Aug 29, 2013 at 15:34
possible duplicate of "Unknown modifier 'g' in..." when using preg_match in PHP? — mario
– mario, Commented Aug 29, 2013 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
– Chris, Commented Aug 29, 2013 at 15:36
as @mario said enable error_reporting as you will be forever having unexplained problems developing with it disabled stackoverflow.com/questions/845021/… — Anigel
– Anigel, Commented Aug 29, 2013 at 15:40

2 revs · Accepted Answer · 2017-05-23 10:27:25Z

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, 2017 at 10:27

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Chris

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Marc B · Accepted Answer · 2013-08-29 15:37:36Z

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, 2013 at 15:37

Marc B

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1 Comment

Chris Over a year ago

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!

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