Req #51881 [NEW]: preg_match: Capturing subpatterns that don't match get empty string.

From: Operating system: Win XP Pro PHP version: 5.3.2 Package: PCRE related Bug Type: Feature/Change Request Bug description:preg_match: Capturing subpatterns that don't match get empty string. Description: ------------ Capturing subpatterns that don't match anything still show an empty string in the match array. Since empty string is a legitimate value, the match array should have null or false instead. The workaround to detect a capturing subpattern not matching anything is to use PREG_OFFSET_CAPTURE and look for offset -1 for the particular subpattern. Test script: --------------- <?php preg_match('%(a)|(b)%','b',$m); var_dump($m); //$m[1] === "" as if the first capturing parentheses matched "" //$m[1] === null would be more appropriate (javascript uses "undefined") -- Edit bug report at http://bugs.php.net/bug.php?id=51881&edit=1 -- Try a snapshot (PHP 5.2): http://bugs.php.net/fix.php?id=51881&r=trysnapshot52 Try a snapshot (PHP 5.3): http://bugs.php.net/fix.php?id=51881&r=trysnapshot53 Try a snapshot (PHP 6.0): http://bugs.php.net/fix.php?id=51881&r=trysnapshot60 Fixed in SVN: http://bugs.php.net/fix.php?id=51881&r=fixed Fixed in SVN and need be documented: http://bugs.php.net/fix.php?id=51881&r=needdocs Fixed in release: http://bugs.php.net/fix.php?id=51881&r=alreadyfixed Need backtrace: http://bugs.php.net/fix.php?id=51881&r=needtrace Need Reproduce Script: http://bugs.php.net/fix.php?id=51881&r=needscript Try newer version: http://bugs.php.net/fix.php?id=51881&r=oldversion Not developer issue: http://bugs.php.net/fix.php?id=51881&r=support Expected behavior: http://bugs.php.net/fix.php?id=51881&r=notwrong Not enough info: http://bugs.php.net/fix.php?id=51881&r=notenoughinfo Submitted twice: http://bugs.php.net/fix.php?id=51881&r=submittedtwice register_globals: http://bugs.php.net/fix.php?id=51881&r=globals PHP 4 support discontinued: http://bugs.php.net/fix.php?id=51881&r=php4 Daylight Savings: http://bugs.php.net/fix.php?id=51881&r=dst IIS Stability: http://bugs.php.net/fix.php?id=51881&r=isapi Install GNU Sed: http://bugs.php.net/fix.php?id=51881&r=gnused Floating point limitations: http://bugs.php.net/fix.php?id=51881&r=float No Zend Extensions: http://bugs.php.net/fix.php?id=51881&r=nozend MySQL Configuration Error: http://bugs.php.net/fix.php?id=51881&r=mysqlcfg