Compare multidimensional arrays in PHP

The simplest way I know:

$a == $b;

Note that you can also use the ===. The difference between them is:

1. With Double equals ==, order is important:

   $a = array(0 => 'a', 1 => 'b');
   $b = array(1 => 'b', 0 => 'a');
   var_dump($a == $b);  // true
   var_dump($a === $b); // false
   

2. With Triple equals ===, types matter:

   $a = array(0, 1);
   $b = array('0', '1');
   var_dump($a == $b);  // true
   var_dump($a === $b); // false
   

Reference: Array operators

function multi_diff($arr1,$arr2){
  $result = array();
  foreach ($arr1 as $k=>$v){
    if(!isset($arr2[$k])){
      $result[$k] = $v;
    } else {
      if(is_array($v) && is_array($arr2[$k])){
        $diff = multi_diff($v, $arr2[$k]);
        if(!empty($diff))
          $result[$k] = $diff;
      }
    }
  }
  return $result;
}

//example:

var_dump(multi_diff(

array(
  "A"=>array(
    "A1"=>array('A1-0','A1-1','A1-2','A1-3'),
    "A2"=>array('A2-0','A2-1','A2-2','A2-3'),
    "A3"=>array('A3-0','A3-1','A3-2','A3-3')
  ),
  "B"=>array(
    "B1"=>array('B1-0','B1-1','B1-2','B1-3'),
    "B2"=>array('B2-0','B2-1','B2-2','B2-3'),
    "B3"=>array('B3-0','B3-1','B3-2','B3-3')
  ),
  "C"=>array(
    "C1"=>array('C1-0','C1-1','C1-2','C1-3'),
    "C2"=>array('C2-0','C2-1','C2-2','C2-3'),
    "C3"=>array('C3-0','C3-1','C3-2','C3-3')
  ),
  "D"=>array(
    "D1"=>array('D1-0','D1-1','D1-2','D1-3'),
    "D2"=>array('D2-0','D2-1','D2-2','D2-3'),
    "D3"=>array('D3-0','D3-1','D3-2','D3-3')
  )
),

array(
  "A"=>array(
    "A1"=>array('A1-0','A1-1','A1-2','A1-3'),
    "A2"=>array('A2-0','A2-1','A2-2','A2-3'),
    "A3"=>array('A3-0','A3-1','A3-2')
  ),
  "B"=>array(
    "B1"=>array('B1-0','B1-2','B1-3'),
    "B2"=>array('B2-0','B2-1','B2-2','B2-3'),
    "B3"=>array('B3-0','B3-1','B3-3')
  ),
  "C"=>array(
    "C1"=>array('C1-0','C1-1','C1-2','C1-3'),
    "C3"=>array('C3-0','C3-1')
  ),
  "D"=>array(
    "D1"=>array('D1-0','D1-1','D1-2','D1-3'),
    "D2"=>array('D2-0','D2-1','D2-2','D2-3'),
    "D3"=>array('D3-0','D3-1','D3-2','D3-3')
  )
)

));

This function will do it all for you.

You can use it to truly compare any 2 arrays of same or totally different structures.

It will return:

Values in array1 not in array2 (more)

Values in array2 not in array1 (less)

Values in array1 and in array2 but different (diff)

//results for array1 (when it is in more, it is in array1 and not in array2. same for less)
function compare_multi_Arrays($array1, $array2){
    $result = array("more"=>array(),"less"=>array(),"diff"=>array());
    foreach($array1 as $k => $v) {
      if(is_array($v) && isset($array2[$k]) && is_array($array2[$k])){
        $sub_result = compare_multi_Arrays($v, $array2[$k]);
        //merge results
        foreach(array_keys($sub_result) as $key){
          if(!empty($sub_result[$key])){
            $result[$key] = array_merge_recursive($result[$key],array($k => $sub_result[$key]));
          }
        }
      }else{
        if(isset($array2[$k])){
          if($v !== $array2[$k]){
            $result["diff"][$k] = array("from"=>$v,"to"=>$array2[$k]);
          }
        }else{
          $result["more"][$k] = $v;
        }
      }
    }
    foreach($array2 as $k => $v) {
        if(!isset($array1[$k])){
            $result["less"][$k] = $v;
        }
    }
    return $result;
}

Another way to do it is to serialize() both of the arrays and compare the strings.

http://php.net/manual/en/function.serialize.php