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<?php $array = ['a', 'b']; $result = []; foreach ($array as $k => $result["prefix_$k"]); var_export($result); $result = []; echo "\n---\n"; foreach ($array as $result["prefix_$v"] => $v); var_export($result);
Output for 8.0.1 - 8.0.30, 8.1.0 - 8.1.28, 8.2.0 - 8.2.19, 8.3.0 - 8.3.7
Warning: Undefined variable $k in /in/iVm1u on line 6 array ( 'prefix_' => 'a', 'prefix_0' => 'b', ) --- array ( 'prefix_a' => 0, 'prefix_b' => 1, )
Output for 7.4.0 - 7.4.33
Notice: Undefined variable: k in /in/iVm1u on line 6 array ( 'prefix_' => 'a', 'prefix_0' => 'b', ) --- array ( 'prefix_a' => 0, 'prefix_b' => 1, )

preferences:
100.13 ms | 402 KiB | 123 Q