How to Implement PHP’s array_replace Without Using Built-In Functions

Introduction

The array_replace function in PHP is used to replace the values of the first array with the values from one or more subsequent arrays. But what if you need to achieve the same result without using this built-in function? In this guide, we’ll show you how to manually implement the behavior of array_replace using basic PHP constructs.

Why Avoid array_replace?

Avoiding built-in functions can be helpful for:

• Learning core PHP concepts.
• Coding challenges that restrict the use of built-in functions.
• Customizing functionality beyond what array_replace offers.

Manual Implementation of array_replace

Code Example:

function customArrayReplace($array1, ...$arrays) {
    // Ensure the first parameter is an array
    if (!is_array($array1)) {
        return [];
    }

    // Start with the first array
    $result = $array1;

    // Iterate through the additional arrays
    foreach ($arrays as $array) {
        if (is_array($array)) {
            foreach ($array as $key => $value) {
                // Replace or add the value from the current array
                $result[$key] = $value;
            }
        }
    }

    return $result;
}

// Example usage
$array1 = ["a" => "apple", "b" => "banana", "c" => "cherry"];
$array2 = ["b" => "blueberry", "d" => "dragonfruit"];
$array3 = ["a" => "apricot", "e" => "elderberry"];

$result = customArrayReplace($array1, $array2, $array3);

print_r($result);

Output:

Array
(
    [a] => apricot
    [b] => blueberry
    [c] => cherry
    [d] => dragonfruit
    [e] => elderberry
)

Explanation of the Code

1. Input Validation: The function ensures the first argument is an array.
2. Start with Base Array: The $result array starts as a copy of $array1.
3. Iterate Through Additional Arrays: For each additional array, key-value pairs are added or replace existing ones in $result.
4. Return Final Array: The modified array is returned as the result.

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