- var_dump: documentation ( source)
- array_merge_recursive: documentation ( source)
<?php
$array1 = [
'a' => 'a',
'submodule_id' => [1]
];
$array2 = [
'a' => 'a',
'submodule_id' => [1]
];
var_dump(array_merge_recursive($array1, $array2));