php regex Unknown modifier '/'

Question

Text:

<a href="http://from.ae/cameras-photo/digital-cameras/samsung-es95-white"><img id="img_28300"

My regex:

/<a href="http://from.ae/cameras-photo/digital-cameras/samsung-es95-white"><img id="img_(.*?)"/mis

Code:

$regex = '/<a href="'.$text.'"><img id="img_(.*?)"/mis';
preg_match($regex, $text, $C);

Error:

Warning: preg_match(): Unknown modifier '/'

Because there are many forward slashes in your `text` variable, i suggest you to use a different modifier. — Avinash Raj, Dec 21 '14 at 14:41
@Kubra what are you trying to achieve? What's your expected output? — Avinash Raj, Dec 21 '14 at 14:49
possible duplicate of [Unknown modifier '/' error in PHP](http://stackoverflow.com/questions/3719915/unknown-modifier-error-in-php) — HamZa, Dec 21 '14 at 16:54

elixenide · Accepted Answer · 2014-12-21T15:02:16.767

5

You have to escape the slashes (/) in the regex:

/<a href="http:\/\/from.ae\/cameras-photo\/digital-cameras\/samsung-es95-white"><img id="img_(.*?)"/mis

Because you used / as your delimiter, PHP assumes everything after the second / is a modifier. In this case, that's another /, which is not a valid modifier.

You can do the escaping with preg_quote, like this:

$text = '<a href="http://from.ae/cameras-photo/digital-cameras/samsung-es95-white"><img id="img_28300"';
$regex = '/'.preg_quote('<a href="http://from.ae/cameras-photo/digital-cameras/samsung-es95-white"><img id="img_', '/').'(.*?)"/mis';
var_dump($regex);
var_dump( preg_match($regex, $text) );

Demo

An even simpler solution, as pointed out in the comments, is just to use a different delimiter. I'm fond of ~, but any character will work:

$text = '<a href="http://from.ae/cameras-photo/digital-cameras/samsung-es95-white"><img id="img_28300"';
$regex = '~<a href="http://from.ae/cameras-photo/digital-cameras/samsung-es95-white"><img id="img_(.*?)"~mis';
var_dump($regex);
var_dump( preg_match($regex, $text) );

Demo

edited Dec 21 '14 at 15:02

answered Dec 21 '14 at 14:39

elixenide

44,308
16
74
100

`$regex = ' – Kubra Dec 21 '14 at 14:41
2

@Kubra: It's better if you take the problem identification made here and use it to write your _own_ code solution. Stack Overflow is not a magic code generator that does your programming work for you. – Lightness Races in Orbit Dec 21 '14 at 14:42
@Kubra Please see my edit; you can do the escaping with [**`preg_quote`**](http://php.net/manual/en/function.preg-quote.php). – elixenide Dec 21 '14 at 14:45
now it has two hrefs. – Avinash Raj Dec 21 '14 at 14:45
@AvinashRaj Yeah, I'm not sure exactly what OP is going for, either. I have tried to clarify. – elixenide Dec 21 '14 at 14:48
2

Quoting is good but using a different delimiter is even better because it keeps the RE clean. However, +1 for mentioning about `preq_quote()` because sometimes one simply cannot avoid it (when the RE is produced using data from external sources, f.e.) – axiac Dec 21 '14 at 14:58

score 2 · Answer 2 · answered Dec 21 '14 at 14:45

2

The easiest way is to use another delimiter than / which can be in regex.

Updated regex could be, for example this one, with ~ as a delimiter:

~<a href="http://from.ae/cameras-photo/digital-cameras/samsung-es95-white"><img id="img_(.*?)"~mis

answered Dec 21 '14 at 14:45

pavel

26,538
10
45
61

score 0 · Answer 3 · answered Dec 21 '14 at 14:56

You could simply use \K with a different php delimiter.

$text = '<a href="http://from.ae/cameras-photo/digital-cameras/samsung-es95-white"><img id="img_28300"';
preg_match('~<a href="http://from.ae/cameras-photo/digital-cameras/samsung-es95-white"><img id="img_\K[^"]*~mis', $text, $out);
echo $out[0];

Output:

score 0 · Answer 4 · answered Dec 21 '14 at 15:00

0

$text = '<a href="http://from.ae/cameras-photo/digital-cameras/samsung-es95-white"><img id="img_28300"';

preg_match('#<img id="img_(.*?)"#', $text,$match);
print_r($match);
echo $match[1];

answered Dec 21 '14 at 15:00

Buse Gönen

238
1
5

php regex Unknown modifier '/'

4 Answers4