What is array_uintersect_uassoc in PHP?

Replicating the behavior of PHP’s array_uintersect_uassoc without using built-in array functions can be a rewarding challenge. This function computes the intersection of arrays by comparing both the keys and values using user-defined callback functions for each.

What Does array_uintersect_uassoc Do?

The function identifies matching elements between arrays based on:

• Key comparison: A custom function to compare keys.
• Value comparison: A separate custom function to compare values.

Here’s how you can manually implement the functionality:

function custom_uintersect_uassoc($array1, $array2, $valueCompareFunc, $keyCompareFunc) {
    $result = []; // Result array to store the intersection.

    // Iterate over the first array.
    foreach ($array1 as $key1 => $value1) {
        foreach ($array2 as $key2 => $value2) {
            // Check if both the key and value match based on the custom functions.
            if ($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 caseSensitiveKeyCompare($key1, $key2) {
    return strcmp($key1, $key2); // Case-sensitive key comparison.
}

function caseInsensitiveValueCompare($value1, $value2) {
    return strcasecmp($value1, $value2); // Case-insensitive value comparison.
}

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

// Call the custom function.
$result = custom_uintersect_uassoc($array1, $array2, 'caseInsensitiveValueCompare', 'caseSensitiveKeyCompare');

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

Output:

Array
(
    [b] => Banana
)

How It Works

1. Key Comparison:
   • The caseSensitiveKeyCompare function ensures that keys are compared case-sensitively. For example, “a” is not equal to “A”.
2. Value Comparison:
   • The caseInsensitiveValueCompare function performs a case-insensitive comparison for values. For example, “Apple” is equal to “apple”.
3. Matching Results:
   • Only the key b in $array1 matches the key b in $array2.
   • The value “Banana” in both arrays matches when compared case-insensitively.

Why Create a Custom Implementation?

• Flexibility: Offers full control over how the keys and values are compared.
• Customization: Allows you to define advanced logic for specific scenarios.
• Learning Opportunity: Helps deepen your understanding of array operations in PHP.

Manually implementing array_uintersect_uassoc without using PHP’s built-in functions allows you to customize how keys and values are compared. It’s especially useful in scenarios requiring more specific behavior than what the default function provides. This approach enhances both your coding skills and your ability to handle complex array operations.

Keep Learning 🙂