Regex matches only once

Question

I have a regex that should rewrite [img]foo.bar[/img] to <img src=foo.bar> and in fact, it does. The problem comes in when I have two or more of those [img]url.ext[/img] in the string. Instead of matching each one separately, it matches the first [img] and the last [/img] and leaves the urls and tags in the middle as part of the src. My php code is $newstring = preg_replace('%\[img\](.+)\[/img\]%', '<img src=${1}>', $string);

a working example is https://www.regex101.com/r/mJ9sM0/1

possible duplicate of [regex matching an open and close tag and a certain text patterns inside that tag](http://stackoverflow.com/questions/6368868/regex-matching-an-open-and-close-tag-and-a-certain-text-patterns-inside-that-tag) — NeronLeVelu, Feb 25 '15 at 15:13

hwnd · Answer 1 · 2015-02-25T14:53:14.940

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The + operator is greedy by default, you need to use +? for a non-greedy match.

$str = preg_replace('~\[img]\s*(.+?)\s*\[/img]~i', '<img src="$1">', $str);

Note: I propose the above — recommending the i flag for case insensitive matching.

edited Feb 25 '15 at 14:53

answered Feb 25 '15 at 14:38

hwnd

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score 4 · Accepted Answer · answered Feb 25 '15 at 14:41

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Use +? instead of + for non-greedy match.

\[img\](.+?)\[/img\]

Demo https://www.regex101.com/r/zW9zJ0/1

+ Will match one of more occurrence. Combined with ?, it will match as least as possible (lazy).

answered Feb 25 '15 at 14:41

Amen Jlili

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score 3 · Answer 3 · edited May 23 '17 at 12:22

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Regular expressions are greedy by default. Try with non-greedy regex, i.e.

preg_replace('%\[img\](.+?)\[/img\]%', '<img src=${1}>', $string);

(Note the ? after the +.)

edited May 23 '17 at 12:22

Community

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answered Feb 25 '15 at 14:38

tsnorri

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Regex matches only once

3 Answers3