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<?php $str = "oAAAoooo"; echo preg_replace_callback( '/([\x00-\x1F\*\(\)\\\\])/', function ($matches) { return "\\".join("", unpack("H2", $matches[1])); }, $str ); $str = "oAAAoooo"; function matches($matches) { return "\\".join("", unpack("H2", $matches[1])); } echo '<br><br>' . mb_ereg_replace_callback( '([\x00-\x1F\*\(\)\\\\])', "matches", $str ); ?>

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