What is array_uintersect_uassoc?

PHP’s array_uintersect_uassoc function computes the intersection of arrays where:

• Values are compared using a user-defined function.
• Keys are also compared using a separate user-defined function.

Custom Implementation

If you’re looking to replicate PHP’s array_uintersect_uassoc function without using built-in array functions, this guide will walk you through a step-by-step manual implementation. This function finds the intersection of arrays based on both keys and values, using user-defined callback functions for comparing both.

Below is the PHP code for a manual implementation of array_uintersect_uassoc:

function custom_uintersect_uassoc($array1, $array2, $valueCompareFunc, $keyCompareFunc) {
    $result = []; // Initialize an empty array for storing the intersection.

    foreach ($array1 as $key1 => $value1) {
        foreach ($array2 as $key2 => $value2) {
            // Compare both keys and values using the provided functions.
            if ($keyCompareFunc($key1, $key2) === 0 && $valueCompareFunc($value1, $value2) === 0) {
                $result[$key1] = $value1; // Add to the result if both match.
                break;
            }
        }
    }

    return $result;
}

// Example comparison functions.
function caseInsensitiveValueCompare($a, $b) {
    return strcasecmp($a, $b); // Case-insensitive comparison for values.
}

function caseSensitiveKeyCompare($a, $b) {
    return strcmp($a, $b); // Case-sensitive comparison for keys.
}

// Example arrays.
$array1 = ["a" => "Apple", "b" => "Banana", "c" => "Cherry"];
$array2 = ["A" => "apple", "b" => "banana", "d" => "Date"];

// Compute the intersection.
$result = custom_uintersect_uassoc($array1, $array2, 'caseInsensitiveValueCompare', 'caseSensitiveKeyCompare');

// Output the result.
print_r($result);

Output:

Array
(
    [b] => Banana
)

Explanation

1. Input Arrays:
   • $array1 contains keys a, b, and c.
   • $array2 contains keys A, b, and d.
2. Comparison Logic:
   • Keys: Compared case-sensitively using caseSensitiveKeyCompare.
   • Values: Compared case-insensitively using caseInsensitiveValueCompare.
3. Result:
   • The key b matches case-sensitively.
   • The corresponding value “Banana” matches case-insensitively.
4. Excluded Items:
   • Key a in $array1 doesn’t match A in $array2 because the comparison is case-sensitive.

Why Use a Custom Implementation?

• Customization: Full control over how keys and values are compared.
• Flexibility: Can handle scenarios where built-in functions are restricted.
• Learning: Deepens your understanding of array operations and custom logic.

Creating a custom array_uintersect_uassoc function allows for advanced comparisons and provides flexibility beyond PHP’s built-in capabilities. This implementation can be tailored to your specific needs, making it a valuable tool for complex array operations.

Keep Learning 🙂