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<?php $arr = array('key' => 'value'); //array_map(function($k, $v){var_dump($k, $v);}, array_keys($arr), $arr); array_map(function($a){ var_dump(key($a)); }, $arr);
Output for 8.2.0 - 8.2.18, 8.3.0 - 8.3.6
Fatal error: Uncaught TypeError: key(): Argument #1 ($array) must be of type array, string given in /in/gCu9Y:7 Stack trace: #0 /in/gCu9Y(7): key('value') #1 [internal function]: {closure}('value') #2 /in/gCu9Y(5): array_map(Object(Closure), Array) #3 {main} thrown in /in/gCu9Y on line 7
Process exited with code 255.
Output for 8.0.0 - 8.0.30, 8.1.0 - 8.1.28
Fatal error: Uncaught TypeError: key(): Argument #1 ($array) must be of type array, string given in /in/gCu9Y:7 Stack trace: #0 /in/gCu9Y(7): key('value') #1 [internal function]: {closure}('value') #2 /in/gCu9Y(8): array_map(Object(Closure), Array) #3 {main} thrown in /in/gCu9Y on line 7
Process exited with code 255.
Output for 5.3.0 - 5.3.29, 5.4.0 - 5.4.45, 5.5.24 - 5.5.35, 5.6.8 - 5.6.28, 7.0.0 - 7.0.20, 7.1.0 - 7.1.20, 7.2.0 - 7.2.33, 7.3.16 - 7.3.33, 7.4.0 - 7.4.33
Warning: key() expects parameter 1 to be array, string given in /in/gCu9Y on line 7 NULL
Output for 4.4.2 - 4.4.9, 5.1.0 - 5.1.6, 5.2.0 - 5.2.17
Parse error: syntax error, unexpected T_FUNCTION, expecting ')' in /in/gCu9Y on line 5
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 T_FUNCTION, expecting ')' in /in/gCu9Y on line 5
Process exited with code 255.
Output for 4.3.2 - 4.3.4
Parse error: parse error, expecting `')'' in /in/gCu9Y on line 5
Process exited with code 255.
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