- array_intersect: documentation ( source)
- var_export: documentation ( source)
<?php
$A = [3,45,67,8];
$B = [ 1 => [1,6,8],
2 => [5,67,3,4,5,66,6],
3 => [55,56,57,58],
4 => [45,80,81,82]
];
$result = [];
foreach ($B as $key => $haystack) {
if (array_intersect($B, $A)) {
$result[] = $key;
}
}
var_export($result);