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<?php $kw = " asdsdfsdf \t as "; $pattern = '/[[:cntrl:]' . preg_quote(',!@%^*()={};~`<>?\|', '/') . ']/u'; var_dump($pattern); var_dump(var_export($pattern, true)); var_dump(preg_match($pattern, $kw));
Output for 4.3.0 - 4.3.11, 4.4.0 - 4.4.9, 5.0.0 - 5.0.5, 5.1.0 - 5.1.6, 5.2.0 - 5.2.17, 5.3.0 - 5.3.29, 5.4.0 - 5.4.45, 5.5.24 - 5.5.35, 5.6.8 - 5.6.28, 7.0.0 - 7.0.20, 7.1.0 - 7.1.10, 7.2.0 - 7.2.33, 7.3.16 - 7.3.33, 7.4.0 - 7.4.33, 8.0.0 - 8.0.30, 8.1.0 - 8.1.28, 8.2.0 - 8.2.18, 8.3.0 - 8.3.6
string(46) "/[[:cntrl:],\!@%\^\*\(\)\=\{\};~`\<\>\?\\\|]/u" string(62) "'/[[:cntrl:],\\!@%\\^\\*\\(\\)\\=\\{\\};~`\\<\\>\\?\\\\\\|]/u'" int(1)

preferences:
230.81 ms | 406 KiB | 310 Q