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<?php $pattern="/\(((?>[^()]+)|(?R))*/\)"; //$str="(def a (x) (+ 1 x))(print (a 1))"; $str="(aaa)"; preg_match_all($pattern,$str,$out); var_dump($out);
Output for 5.2.3 - 5.2.17, 5.3.0 - 5.3.29, 5.4.0 - 5.4.45, 5.5.0 - 5.5.35, 5.6.0 - 5.6.28, 7.0.0 - 7.0.20, 7.1.0 - 7.1.10, 7.2.0 - 7.2.33, 7.3.12 - 7.3.33, 7.4.0 - 7.4.33, 8.0.0 - 8.0.30, 8.1.0 - 8.1.27, 8.2.0 - 8.2.17, 8.3.0 - 8.3.4
Warning: preg_match_all(): Unknown modifier '\' in /in/f5ZYH on line 9 NULL
Output for 5.2.0 - 5.2.2
<br /> <b>Warning</b>: preg_match_all() [<a href='function.preg-match-all'>function.preg-match-all</a>]: Unknown modifier '\' in <b>/in/f5ZYH</b> on line <b>9</b><br /> NULL
Output for 4.4.3 - 4.4.9, 5.0.0 - 5.0.5, 5.1.0 - 5.1.6
<br /> <b>Warning</b>: preg_match_all() [<a href='function.preg-match-all'>function.preg-match-all</a>]: Unknown modifier '\' in <b>/in/f5ZYH</b> on line <b>9</b><br /> array(0) { }
Output for 4.3.11, 4.4.0 - 4.4.2
<br /> <b>Warning</b>: preg_match_all(): Unknown modifier '\' in <b>/in/f5ZYH</b> on line <b>9</b><br /> array(0) { }
Output for 4.3.0 - 4.3.10
<br /> <b>Warning</b>: Unknown modifier '\' in <b>/in/f5ZYH</b> on line <b>9</b><br /> array(0) { }

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