How to Implement array_pop in PHP Without Using Built-In Functions

The array_pop function in PHP removes and returns the last element of an array, reducing its size by one. While it’s simple to use, there might be scenarios where you need to implement its functionality manually, such as for learning purposes or when avoiding built-in PHP functions. This article demonstrates how to create your own array_pop function.

What Is array_pop?

The array_pop function performs two main tasks:

1. Removes the last element from an array.
2. Returns the removed element.

In our custom implementation, we will replicate these actions using basic PHP constructs.

Step 1: Define the Custom Function

Here is how you can create a custom array_pop function:

function customArrayPop(&$array) {
    $length = count($array);
    
    // If the array is empty, return null
    if ($length === 0) {
        return null;
    }
    
    // Get the last element
    $lastElement = $array[$length - 1];
    
    // Remove the last element
    unset($array[$length - 1]);
    
    // Reindex the array to maintain numeric keys
    $array = array_values($array);
    
    // Return the removed element
    return $lastElement;
}

Step 2: Test the Custom Function

Here’s an example of how to use this custom array_pop function:

// Example array
$numbers = [10, 20, 30, 40];

// Use the custom array_pop function
$poppedValue = customArrayPop($numbers);

// Display the results
echo "Popped Value: " . $poppedValue . "\n";
echo "Remaining Array: ";
print_r($numbers);

Output:

Popped Value: 40
Remaining Array: Array
(
    [0] => 10
    [1] => 20
    [2] => 30
)

How It Works

1. The function calculates the length of the array using count().
2. It retrieves the last element using its index.
3. The unset() function removes the last element from the array.
4. The array_values() function reindexes the array to maintain numeric keys.
5. Finally, the removed element is returned.

By building your own array_pop function in PHP, you gain a deeper understanding of how arrays work under the hood. While built-in functions like array_pop are optimized for efficiency, custom implementations can help you learn and adapt to specific requirements.

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