array_diff() with multidimensional arrays

Question

I have an array containing rows of associative data.

$array1 = array(     array('ITEM' => 1),     array('ITEM' => 2),     array('ITEM' => 3), ); 

I have a second array, also containing rows of associative data, that I would like to filter using the first array.

$array2 = array(     array('ITEM' => 2),     array('ITEM' => 3),     array('ITEM' => 1),     array('ITEM' => 4), ); 

This feels like a job for array_diff(), but how can I compare the rows exclusively on the deeper ITEM values?

How can I filter the second array and get the following result?

array(3 => array('ITEM' => 4)) 

Answer 1

You can define a custom comparison function using array_udiff().

function udiffCompare($a, $b) {     return $a['ITEM'] - $b['ITEM']; }  $arrdiff = array_udiff($arr2, $arr1, 'udiffCompare'); print_r($arrdiff); 

Output:

Array (     [3] => Array         (             [ITEM] => 4         ) ) 

This uses and preserves the arrays' existing structure, which I assume you want.