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<?php $foo = [  'a' => '1',  'b' => '1',  'c' => '2', ]; function change_keys($array, $callback) {   $temp = array_map($callback, array_combine(array_keys($array), array_keys($array)));   return array_combine($temp, $array); } $new_array = change_keys($foo, function($v) {   return '#' . $v; }); var_dump($new_array);
Output for 5.4.0 - 5.4.32
Parse error: syntax error, unexpected ''a'' (T_CONSTANT_ENCAPSED_STRING), expecting ']' in /in/s8Da6 on line 15
Process exited with code 255.
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/s8Da6 on line 14
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/s8Da6 on line 14
Process exited with code 255.
Output for 4.3.2 - 4.3.4
Parse error: parse error in /in/s8Da6 on line 14
Process exited with code 255.

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