array_intersect, but for a sub-arrays of a single array variable

Question

I've got an array that looks like this:

$foo = array(
    0 => array('a', 'b', 'c', 'd'),
    1 => array('b', 'c', 'd'),
    2 => array('b', 'd', 'f')
)

I'll refer to $foo[0], $foo[1], and $foo[2] as sub-arrays.

I basically need to perform an array_intersect() across all 3 sub-arrays in $foo. The result should be:

array('b', 'd')

As all three sub-arrays had these values in common. What is the best way to do this?

Some considerations:

• There will always be at least one sub-array. No upper limit.
• If only one sub-array is provided, it should return that sub-array
• If there aren't any common values in all the sub-arrays, an empty array should be returned
• If this functionality already exists as a PHP function, I will /facepalm

Answer 1

$intersect = call_user_func_array('array_intersect',$foo);

Note that keys are preserved from $foo[0]