Question

I was wondering if there is a native PHP function for returning an array made up of of a certain set of given key=>value elements from another array, given a list of require keys. Here’s what I mean:

// Nice information
$source_array = array('a' => 'hello', 'b' => 'goodbye', 'c' => 'good day', 'd' => 'sunshine');

// Required element keys
$array_two = array('a','b');
$array_three = array('a','d');

// Get that stuff from $source_array...
// $array_two_result = ???
// $array_three_result = ???

// Show it
print_r($array_two_result);
print_r($array_three_result);

Outputs:

Array(
    [a] => 'hello'
    [b] => 'goodbye'
)
Array(
    [a] => 'hello'
    [d] => 'sunshine'
)

I’ve been looking through the documentation but can’t find anything as of yet, but it doesn’t seem to me like a particularly deviant thing to want to do, hence the question.

Answer 1

This seems to be what you are looking for: array_intesect_key

$source_array = array('a' => 'hello', 'b' => 'goodbye', 'c' => 'good day', 'd' => 'sunshine');

// Required element keys
$array_two = array('a','b');
$array_three = array('a','d');

// Get that stuff from $source_array...
$array_two_result = array_intersect_key($source_array, array_flip($array_two));
$array_three_result = array_intersect_key($source_array, array_flip($array_three));

// Show it
print_r($array_two_result);
print_r($array_three_result);