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run code in 500+ PHP versions simultaneously
<?php $array = [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,100]; $result = []; foreach($array as $num){ if(strlen($num) < 2){ $result[] = $num; }else{ $parts = str_split($num); $result = array_merge($result,$parts); } } print_r($result); ?>
Output for 5.6.0, 7.1.25 - 7.1.33, 7.2.0 - 7.2.33, 7.3.0 - 7.3.33, 7.4.0 - 7.4.33, 8.0.0 - 8.0.30, 8.1.0 - 8.1.34, 8.2.0 - 8.2.30, 8.3.0 - 8.3.30, 8.4.1 - 8.4.18, 8.5.0 - 8.5.3
Array ( [0] => 1 [1] => 2 [2] => 3 [3] => 4 [4] => 5 [5] => 6 [6] => 7 [7] => 8 [8] => 9 [9] => 1 [10] => 0 [11] => 1 [12] => 1 [13] => 1 [14] => 2 [15] => 1 [16] => 3 [17] => 1 [18] => 4 [19] => 1 [20] => 5 [21] => 1 [22] => 0 [23] => 0 )

preferences:
95.7 ms | 1565 KiB | 4 Q