array_udiff(): Difference between two arrays comparing values through callback function

$new_array = array_udiff ($array1, $array2,....,my_function());

Example with two arrays

function my_function($a, $b)
{
    if ($a === $b) {
        return 0;
    }
    return ($a > $b)? 1:-1;
}

$first=array('One' =>'First','Two'=>'Second','Three'=>'Third','Fourth');
$second=array('One'=> 'First','2nd','Third');

$result=array_udiff($first,$second,"my_function");
while (list ($key, $val) = each ($result)) {
echo "$key -> $val <br>";
}

Two -> Second 
0 -> Fourth  

Example 2: Comparing Multi-dimensional Arrays

We can use array_udiff() with multi-dimensional arrays to find differences between arrays based on specific keys:

function compare_arrays($a, $b) {
    return strcmp($a['name'], $b['name']);
}

$array1 = [
    ['name' => 'John', 'age' => 25],
    ['name' => 'Alice', 'age' => 30]
];
$array2 = [
    ['name' => 'John', 'age' => 27],
    ['name' => 'Bob', 'age' => 35]
];

$result = array_udiff($array1, $array2, 'compare_arrays');
print_r($result);

Example 3: Ignoring Case Sensitivity During Comparison

To compare arrays while ignoring case, use strcasecmp() in the callback:

function compare_ignore_case($a, $b) {
    return strcasecmp($a, $b);
}

$array1 = ['First', 'Second', 'third'];
$array2 = ['first', 'Second', 'Third'];

$result = array_udiff($array1, $array2, 'compare_ignore_case');
print_r($result);

Use Case: Finding Unique Objects in Arrays

By comparing object properties, we can find unique objects across arrays:

class Person {
    public $name;
    public function __construct($name) {
        $this->name = $name;
    }
}

function compare_objects($a, $b) {
    return strcmp($a->name, $b->name);
}

$array1 = [new Person('John'), new Person('Alice')];
$array2 = [new Person('John'), new Person('Bob')];

$result = array_udiff($array1, $array2, 'compare_objects');
print_r($result);

Subhendu Mohapatra

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