Custom Implementation of array_diff_uassoc Without PHP Array Functions

To replicate the functionality of array_diff_uassoc in PHP without using PHP’s built-in array functions, you can create a custom function. This function compares two arrays by both key and value, using a user-defined callback function for comparison.

Here’s how you can do it:

Custom Implementation of array_diff_uassoc

<?php
function custom_array_diff_uassoc($array1, $array2, $keyCompareCallback) {
    $result = [];

    // Iterate through the first array
    foreach ($array1 as $key1 => $value1) {
        $keyExists = false;

        // Iterate through the second array
        foreach ($array2 as $key2 => $value2) {
            // Use the custom callback to compare keys
            if ($keyCompareCallback($key1, $key2) === 0 && $value1 === $value2) {
                $keyExists = true;
                break;
            }
        }

        // If no matching key and value found, add to result
        if (!$keyExists) {
            $result[$key1] = $value1;
        }
    }

    return $result;
}

// Example callback for case-sensitive key comparison
$keyCompareCallback = function($key1, $key2) {
    return strcmp($key1, $key2); // Case-sensitive comparison
};

// Example usage
$array1 = ['a' => 1, 'b' => 2, 'c' => 3];
$array2 = ['b' => 2, 'd' => 4];

$difference = custom_array_diff_uassoc($array1, $array2, $keyCompareCallback);
print_r($difference);
?>

Output:

Array
(
    [a] => 1
    [c] => 3
)

Explanation:

1. Input:
   • $array1 and $array2: The arrays to compare.
   • $keyCompareCallback: A user-defined function to compare keys.
2. Iteration:
   • The outer loop iterates over each key-value pair in $array1.
   • The inner loop checks each key-value pair in $array2 for matches.
3. Comparison:
   • The keys are compared using the callback function.
   • The values are compared with the === operator for strict comparison.
4. Result Construction:
   • If a key-value pair in $array1 does not have a match in $array2, it is added to the $result array.
5. Output:
   • The $result array contains the key-value pairs from $array1 that are not in $array2 based on the custom comparison.

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