What is array_uintersect_assoc?

The array_uintersect_assoc function in PHP is used to compute the intersection of arrays based on both keys and values, with the values compared using a user-defined callback function.

Custom Implementation

Below is the code for a custom implementation of this function:

function custom_uintersect_assoc($array1, $array2, $compareFunc) {
    $result = []; // Initialize an empty array to store the intersection.

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

    return $result;
}

// Example comparison function (case-insensitive string comparison).
function caseInsensitiveCompare($a, $b) {
    return strcasecmp($a, $b); // Returns 0 if $a is equal to $b.
}

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

// Compute the intersection.
$result = custom_uintersect_assoc($array1, $array2, 'caseInsensitiveCompare');

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

Output:

Array
(
    [a] => Apple
    [b] => Banana
)

Explanation

1. Input Arrays:
   • $array1 has keys a, b, and c with corresponding values.
   • $array2 has keys a, b, and d.
2. Logic:
   • Each key-value pair in $array1 is compared with every key-value pair in $array2.
   • The caseInsensitiveCompare function ensures that string comparisons ignore case.
3. Result:
   • Keys a and b are present in both arrays, and their values match when compared case-insensitively.

Why Use a Custom Implementation?

• Flexibility: You can control how comparisons are made.
• Learning Opportunity: It helps you understand the underlying logic of array operations.
• Limitations of Built-in Functions: In some scenarios, built-in functions may not provide the exact functionality you need.

Creating a custom implementation of array_uintersect_assoc without built-in functions allows you to fully understand how array intersections work. This manual approach is also useful in cases where PHP’s built-in functions are restricted or unavailable.

Keep Learning 🙂