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<?php $regexEncoding = 'UTF-32'; mb_regex_encoding( $regexEncoding ); var_export( mb_ereg_replace( mb_convert_encoding( '(.+)', $regexEncoding ), mb_convert_encoding( "the \\1", $regexEncoding ), mb_convert_encoding( 'dog', $regexEncoding ) ) );
based on XPh9S
Output for 7.1.25 - 7.1.33, 7.2.0 - 7.2.33, 7.3.0 - 7.3.26, 7.4.0 - 7.4.14, 8.0.0
'' . "\0" . '' . "\0" . '' . "\0" . 't' . "\0" . '' . "\0" . '' . "\0" . 'h' . "\0" . '' . "\0" . '' . "\0" . 'e' . "\0" . '' . "\0" . '' . "\0" . ' ' . "\0" . '' . "\0" . '' . "\0" . '\\' . "\0" . '' . "\0" . '' . "\0" . '1'