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<?php $a = 1; unset($a); var_dump(isset($a)); var_dump(!isset($a)); var_dump(empty($a)); var_dump(is_null($a));
Output for 5.0.4 - 7.1.0
bool(false) bool(true) bool(true) Notice: Undefined variable: a in /in/RtIm9 on line 11 bool(true)
Output for 4.3.0 - 5.0.3
bool(false) bool(true) bool(true) Notice: Undefined variable: a in /in/RtIm9 on line 11 bool(true)