检查数组是否在两个多维数组中

Question

I have two multidimensional arrays:

Haystack

$haystack = array (
  0 => array (
    "child_element_id" => 11
    "answer_id" => 15
  ),
  1 => array (
    "child_element_id" => 12
    "answer_id" => 17
  ),
  2 => array (
    "child_element_id" => 13
    "answer_id" => 21
  )
)

Needle

 $needle = array (
  0 => array (
    "child_element_id" => 12
    "answer_id" => 17
  ),
  1 => array (
    "child_element_id" => 13
    "answer_id" => 21
  )
)

I want to check if all the key values from array "Needle" exists in the array "Haystack". What's the best practice for this? Thank you!

Answer 1

Pretty easy using in_array() since needle can be an array:

$found = 0;
foreach($needle as $array) {
    if(in_array($array, $haystack, true)) {
        $found++;
    }
}
if($found === count($needle)) {
    echo 'all needles were found in haystack';
}

Or maybe:

$found = true;
foreach($needle as $array) {
    if(!in_array($array, $haystack, true)) {
        $found = false;
        break;
    }
}
if($found) {
    echo 'all needles were found in haystack';
}

You could even use array_search() as you can use an array for needle as well, no need to run two loops.

Using serialize():

if(count(array_map('unserialize',
         array_intersect(array_map('serialize', $needle), 
                         array_map('serialize',$haystack)))) == count($needle))
{
                             echo 'all needles were found in haystack';
}

• serialize() the inner arrays of both arrays and compute the intersection (common inner arrays)
• unserialize() the result and compare the count() with the count of $needle