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<?php $a = []; $b = array_merge([4 => 1], $a); var_dump($b); $a = []; $b = [4 => 1] + $a; var_dump($b);
Output for 8.2.31, 8.3.0 - 8.3.31, 8.4.1 - 8.4.22, 8.5.0 - 8.5.7
array(1) { [0]=> int(1) } array(1) { [4]=> int(1) }
preferences:
47.36 ms | 731 KiB | 4 Q