Recursive Array_Diff()

recursive array_diff()?

There is one such function implemented in the comments of array_diff.

function arrayRecursiveDiff($aArray1, $aArray2) {
  $aReturn = array();

  foreach ($aArray1 as $mKey => $mValue) {
    if (array_key_exists($mKey, $aArray2)) {
      if (is_array($mValue)) {
        $aRecursiveDiff = arrayRecursiveDiff($mValue, $aArray2[$mKey]);
        if (count($aRecursiveDiff)) { $aReturn[$mKey] = $aRecursiveDiff; }
      } else {
        if ($mValue != $aArray2[$mKey]) {
          $aReturn[$mKey] = $mValue;
        }
      }
    } else {
      $aReturn[$mKey] = $mValue;
    }
  }
  return $aReturn;
} 

The implementation only handles two arrays at a time, but I do not think that really posses a problem. You could run the diff sequentially if you need the diff of 3 or more arrays at a time. Also this method uses key checks and does a loose verification.

Recursive Difference of Arrays with Changed Array Order

You can achieve that by using array_diff, array_column and array_map:

$col = "projectId";
$res = array_diff(array_column($a, $col), array_column($b, $col));
$res = array_map(function($id) use ($col) {return [$col => $id];}, $res);

Reference: array-diff, array-column, array_map

Live example: 3v4l

PHP array diff recursively (multidimensional) only on the keys

function array_key_recursive_compare($array1, $array2) {
    $diff = false;
        // Left-to-right
        foreach ($array1 as $key => $value) {
            if (!array_key_exists($key,$array2)) {
                $diff[0][$key] = $value;
            } elseif (is_array($value)) {
                if (!is_array($array2[$key])) {
                    $diff[0][$key] = $value;
                    $diff[1][$key] = $array2[$key];
                } else {
                    $new = array_compare($value, $array2[$key]);
                    if ($new !== false) {
                        if (isset($new[0]))
                            $diff[0][$key] = $new[0];
                        if (isset($new[1]))
                            $diff[1][$key] = $new[1];
                    };
                };
            } elseif ($array2[$key] !== $value) {
                $diff[0][$key] = $value;
                $diff[1][$key] = $array2[$key];
            };
        };
        // Right-to-left
        foreach ($array2 as $key => $value) {
            if (!array_key_exists($key,$array1)) {
                $diff[1][$key] = $value;
            }
            // No direct comparison because matching keys were compared in the
            // left-to-right loop earlier, recursively.
        }
        return $diff;
    }

Multidimensional Array Diff Recursive not working in PHP

Apart from the fact that this could probably be solved in one sql query, here is a way of using php built in functions. Which are much faster than anything you can write.

When fetching data from DB use stone_ids as keys

$allMilestone[$row['stone_id']] = $row;
// and 
$checkedMilestone[$row['stone_id']] = $row;

or something like this. I am not fluent in php mysql driver use, but there probably is a function that returns associaltive array. If not than write out your select statements properly like SELECT stone_id, ... FROM ... and use:

$allMilestone[$row[0]] = $row;
// and 
$checkedMilestone[$row[0]] = $row;

Later you can use array_diff_key() function to have ... the difference !

array_diff not always correct

This is working correct. According to array_diff() documentation:

array array_diff ( array $array1 , array $array2 [, array $... ] )

Compares array1 against one or more other arrays and returns the
values in array1 that are not present in any of the other arrays.

Another important info from documentation:

Two elements are considered equal if and only if (string) $elem1 ===
(string) $elem2. In words: when the string representation is the same.

So in $answers array there are no k, B, Y elements of $fields array.

Why does array_diff on arrays of arrays return an empty array?

From the documentation:

Two elements are considered equal if and only if (string) $elem1 === (string) $elem2. In words: when the string representation is the same.

echo (string) array(); gives you just Array, so for array_diff, your arrays look like:

$array1 = array('Array', 'Array');
$array2 = array('Array');

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So to create a diff for your arrays, you would need something like this (assuming that every element in the arrays is itself an array):

$diff = array();

foreach($array1 as $val1) {
    $contained = false;
    foreach($array2 as $val2) {
        if(count(array_diff($val1, $val2)) == 0) {
            $contained = true; 
            break;
        }
    }
    if(!$contained) {
        $diff[] = $val1;
    }
}

Disclaimer: This is more or less just a sketch.

php compare two nested array and predict the difference

$results = array_diff(array_map('serialize',$a2),array_map('serialize',$a1));
$results = array_map('unserialize',$results);

echo '<pre>';
print_r($results);

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