php - find duplicate value in multi-dimensional array

Question

From a function I am given a multidimensional array like this:

array(
    [0] => array(
        [0] => 7,
        [1] => 18
    ),
    [1] => array(
        [0] => 12,
        [1] => 7
    ),
    [2] => array(
        [0] => 12,
        [1] => 7,
        [2] => 13
    )
)

I need to find duplicate values in the 3 arrays within the main array. For example, if value 7 repeats in the 3 arrays, return 7.

Answer 1

<?php
$array = array(array(7,18), array(12,7), array(12, 7, 13));
$result = array();


$first = $array[0];
for($i=1; $i<count($array); $i++){
 $result = array_intersect ($first, $array[$i]);
 $first = $result;
}
print_r($result);//7
?>