Req #60944 [NEW]: Unable to detect if variable exists vs. is null

From: Operating system: Linux PHP version: 5.3.9 Package: Variables related Bug Type: Feature/Change Request Bug description:Unable to detect if variable exists vs. is null Description: ------------ There is no difference between $x = NULL and unset($a). So i'm unable to detect if variable was defined (so it can be defined and be filled with null) http://www.php.net/manual/en/types.comparisons.php Table Comparisons of $x with PHP functions, rows 2 - 4 gives same results Expected result: ---------------- Different results for undefined variables and null variables -- Edit bug report at https://bugs.php.net/bug.php?id=60944&edit=1 -- Try a snapshot (PHP 5.4): https://bugs.php.net/fix.php?id=60944&r=trysnapshot54 Try a snapshot (PHP 5.3): https://bugs.php.net/fix.php?id=60944&r=trysnapshot53 Try a snapshot (trunk): https://bugs.php.net/fix.php?id=60944&r=trysnapshottrunk Fixed in SVN: https://bugs.php.net/fix.php?id=60944&r=fixed Fixed in SVN and need be documented: https://bugs.php.net/fix.php?id=60944&r=needdocs Fixed in release: https://bugs.php.net/fix.php?id=60944&r=alreadyfixed Need backtrace: https://bugs.php.net/fix.php?id=60944&r=needtrace Need Reproduce Script: https://bugs.php.net/fix.php?id=60944&r=needscript Try newer version: https://bugs.php.net/fix.php?id=60944&r=oldversion Not developer issue: https://bugs.php.net/fix.php?id=60944&r=support Expected behavior: https://bugs.php.net/fix.php?id=60944&r=notwrong Not enough info: https://bugs.php.net/fix.php?id=60944&r=notenoughinfo Submitted twice: https://bugs.php.net/fix.php?id=60944&r=submittedtwice register_globals: https://bugs.php.net/fix.php?id=60944&r=globals PHP 4 support discontinued: https://bugs.php.net/fix.php?id=60944&r=php4 Daylight Savings: https://bugs.php.net/fix.php?id=60944&r=dst IIS Stability: https://bugs.php.net/fix.php?id=60944&r=isapi Install GNU Sed: https://bugs.php.net/fix.php?id=60944&r=gnused Floating point limitations: https://bugs.php.net/fix.php?id=60944&r=float No Zend Extensions: https://bugs.php.net/fix.php?id=60944&r=nozend MySQL Configuration Error: https://bugs.php.net/fix.php?id=60944&r=mysqlcfg