array_udiff_uassoc(): compare arrays based on custom rules for both data and keys

The array_udiff_uassoc() function in PHP is used to compare arrays and compute the difference using user-defined comparison functions for both data and keys. This is especially useful when you need fine-grained control over how values and keys are compared between arrays.

Syntax

array_udiff_uassoc(array $array1, array ...$arrays, callable $value_compare_func, callable $key_compare_func): array

• $array1: The first array to compare.
• $arrays: One or more arrays to compare against the first array.
• $value_compare_func: A callback function to compare the data of the arrays.
• $key_compare_func: A callback function to compare the keys of the arrays.

Example 1: Basic Use of array_udiff_uassoc()

$array1 = ['a' => 'apple', 'b' => 'banana', 'c' => 'cherry'];
$array2 = ['a' => 'apple', 'b' => 'grape', 'c' => 'cherry'];

$result = array_udiff_uassoc(
    $array1,
    $array2,
    function($a, $b) {
        return strcmp($a, $b);
    },
    function($a, $b) {
        return strcmp($a, $b);
    }
);

print_r($result);

Array
(
    [b] => banana
)

Example 2: Comparing Arrays with Case-Insensitive Key Comparison

$array1 = ['A' => 'apple', 'B' => 'banana', 'C' => 'cherry'];
$array2 = ['a' => 'apple', 'b' => 'grape', 'C' => 'cherry'];

$result = array_udiff_uassoc(
    $array1,
    $array2,
    function($a, $b) {
        return strcmp($a, $b);
    },
    function($a, $b) {
        return strcasecmp($a, $b);
    }
);

print_r($result);

Array
(
    [B] => banana
)

Example 3: Custom Data and Key Comparison Using Length

$array1 = ['apple' => 'red', 'banana' => 'yellow', 'cherry' => 'red'];
$array2 = ['apple' => 'green', 'grape' => 'purple', 'cherry' => 'dark red'];

$result = array_udiff_uassoc(
    $array1,
    $array2,
    function($a, $b) {
        return strlen($a) - strlen($b);
    },
    function($a, $b) {
        return strlen($a) - strlen($b);
    }
);

print_r($result);

Array
(
    [apple] => red
	[banana] => yellow
    [cherry] => red
)

Conclusion

The array_udiff_uassoc() function provides the flexibility to compare arrays with custom rules for both values and keys. Whether you need to perform case-insensitive comparisons or use more complex logic like length-based comparisons, this function helps you maintain fine control over the comparison process. It's especially useful for dealing with associative arrays where both data and key differences matter.