3v4l.org

run code in 300+ PHP versions simultaneously
<?php $root = array( 1=>'cat1', 2=>'cat2', 3=>'cat3' ); $child_1 = array( 1=>'sub_cat1', 2=>'sub_cat2', 3=>'sub_cat3' ); $child_2 = array( 1=>'sub_sub_cat1', 2=>'sub_sub_cat2', 3=>'sub_sub_cat3' ); function getAllCombinationsArray($source_arrays = array(), $key = '', $value = ''){ $return = array(); foreach(array_shift($source_arrays) as $ck => $cv) { if(!empty($source_arrays)) { $return += getAllCombinationsArray($source_arrays, $key.$ck.'_', $value.$cv.' -> '); } else { $return[$key.$ck] = $value.$cv; } } return $return; } print_r(getAllCombinationsArray(array($root, $child_1, $child_2)));
Output for 4.3.0 - 4.3.11, 4.4.0 - 4.4.9, 5.0.0 - 5.0.5, 5.1.0 - 5.1.6, 5.2.0 - 5.2.17, 5.3.0 - 5.3.29, 5.4.0 - 5.4.45, 5.5.24 - 5.5.35, 5.6.7 - 5.6.28, 7.0.0 - 7.0.20, 7.1.0 - 7.1.20, 7.2.0 - 7.2.33, 7.3.16 - 7.3.33, 7.4.0 - 7.4.33, 8.0.0 - 8.0.30, 8.1.0 - 8.1.28, 8.2.0 - 8.2.18, 8.3.0 - 8.3.6
Array ( [1_1_1] => cat1 -> sub_cat1 -> sub_sub_cat1 [1_1_2] => cat1 -> sub_cat1 -> sub_sub_cat2 [1_1_3] => cat1 -> sub_cat1 -> sub_sub_cat3 [1_2_1] => cat1 -> sub_cat2 -> sub_sub_cat1 [1_2_2] => cat1 -> sub_cat2 -> sub_sub_cat2 [1_2_3] => cat1 -> sub_cat2 -> sub_sub_cat3 [1_3_1] => cat1 -> sub_cat3 -> sub_sub_cat1 [1_3_2] => cat1 -> sub_cat3 -> sub_sub_cat2 [1_3_3] => cat1 -> sub_cat3 -> sub_sub_cat3 [2_1_1] => cat2 -> sub_cat1 -> sub_sub_cat1 [2_1_2] => cat2 -> sub_cat1 -> sub_sub_cat2 [2_1_3] => cat2 -> sub_cat1 -> sub_sub_cat3 [2_2_1] => cat2 -> sub_cat2 -> sub_sub_cat1 [2_2_2] => cat2 -> sub_cat2 -> sub_sub_cat2 [2_2_3] => cat2 -> sub_cat2 -> sub_sub_cat3 [2_3_1] => cat2 -> sub_cat3 -> sub_sub_cat1 [2_3_2] => cat2 -> sub_cat3 -> sub_sub_cat2 [2_3_3] => cat2 -> sub_cat3 -> sub_sub_cat3 [3_1_1] => cat3 -> sub_cat1 -> sub_sub_cat1 [3_1_2] => cat3 -> sub_cat1 -> sub_sub_cat2 [3_1_3] => cat3 -> sub_cat1 -> sub_sub_cat3 [3_2_1] => cat3 -> sub_cat2 -> sub_sub_cat1 [3_2_2] => cat3 -> sub_cat2 -> sub_sub_cat2 [3_2_3] => cat3 -> sub_cat2 -> sub_sub_cat3 [3_3_1] => cat3 -> sub_cat3 -> sub_sub_cat1 [3_3_2] => cat3 -> sub_cat3 -> sub_sub_cat2 [3_3_3] => cat3 -> sub_cat3 -> sub_sub_cat3 )

preferences:
228.29 ms | 408 KiB | 312 Q