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run code in 200+ php & hhvm versions
Bugs & Features
<?php $a = array(1); for ($mppb_times = 4; $mppb_times>0; $mppb_times--) $a = array_merge($a, $a); print_r($a);
based on Vo7WW
Output for 4.3.0 - 7.1.7
Array ( [0] => 1 [1] => 1 [2] => 1 [3] => 1 [4] => 1 [5] => 1 [6] => 1 [7] => 1 [8] => 1 [9] => 1 [10] => 1 [11] => 1 [12] => 1 [13] => 1 [14] => 1 [15] => 1 )