Manual Implementation of array_udiff_uassoc Without Built-in Functions

The array_udiff_uassoc function in PHP compares the values of two arrays using one callback function and the keys using another callback function, returning the differences. Here’s how you can manually implement it without using PHP’s built-in functions.

<?php
// Function to replicate array_udiff_uassoc
function manualArrayUdiffUassoc($array1, $array2, $valueCallback, $keyCallback) {
    $result = []; // Initialize an empty result array

    foreach ($array1 as $key1 => $value1) {
        $isUnique = true;

        foreach ($array2 as $key2 => $value2) {
            // Compare both keys and values using their respective callbacks
            if ($keyCallback($key1, $key2) === 0 && $valueCallback($value1, $value2) === 0) {
                $isUnique = false;
                break;
            }
        }

        // Add to result if unique
        if ($isUnique) {
            $result[$key1] = $value1;
        }
    }

    return $result; // Return the resulting array
}

// Example usage
$array1 = ["a" => 10, "b" => 20, "c" => 30];
$array2 = ["a" => 10, "b" => 25, "d" => 40];

// Custom comparison function for values
$valueCallback = function($a, $b) {
    return $a <=> $b; // Standard three-way comparison
};

// Custom comparison function for keys
$keyCallback = function($a, $b) {
    return strcmp($a, $b); // String comparison
};

$result = manualArrayUdiffUassoc($array1, $array2, $valueCallback, $keyCallback);

echo "The difference with custom value and key comparison is: ";
print_r($result);
?>

Output:

The difference with custom value and key comparison is: Array
(
    [b] => 20
    [c] => 30
)

Explanation:

1. Input Arrays: Two associative arrays are passed, along with separate callback functions for keys and values.
2. Key and Value Comparison:
   • The value callback compares the values.
   • The key callback compares the keys.
3. Custom Logic: Differences are identified only if both the key and value comparisons indicate uniqueness.
4. Result: The resulting array contains key-value pairs from $array1 that are unique based on the custom logic.

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