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<?php $arr = []; $arr['key'] = NULL; var_dump(isset($arr['key'])); //bool(false) var_dump(is_null($arr['key'])); //bool(true) var_dump(is_null($arr['any_key']));
Output for 8.0.0 - 8.0.3
bool(false) bool(true) Warning: Undefined array key "any_key" in /in/g5d1V on line 12 bool(true)
Output for 5.4.0 - 5.4.45, 5.5.0 - 5.5.38, 5.6.0 - 5.6.40, 7.0.0 - 7.0.33, 7.1.0 - 7.1.33, 7.2.0 - 7.2.33, 7.3.0 - 7.3.28, 7.4.0 - 7.4.16
bool(false) bool(true) Notice: Undefined index: any_key in /in/g5d1V on line 12 bool(true)
Output for 4.4.2 - 4.4.9, 5.1.0 - 5.1.6, 5.2.0 - 5.2.17, 5.3.0 - 5.3.29
Parse error: syntax error, unexpected '[' in /in/g5d1V on line 3
Process exited with code 255.
Output for 4.3.0 - 4.3.1, 4.3.5 - 4.3.11, 4.4.0 - 4.4.1, 5.0.0 - 5.0.5
Parse error: parse error, unexpected '[' in /in/g5d1V on line 3
Process exited with code 255.
Output for 4.3.2 - 4.3.4
Parse error: parse error in /in/g5d1V on line 3
Process exited with code 255.