PHP Exercises: Compute the difference between the largest and smallest values in a given array of integers and length one or more

<?php
// Define a function named 'test' that takes an array of numbers as a parameter
function test($nums)
 { 
    // Initialize variables $small_num and $biggest_num with values of 0
    $small_num = 0;
    $biggest_num = 0;

    // Check if the array has elements (size greater than 0)
    if (sizeof($nums) > 0) 
        // If true, set both $small_num and $biggest_num to the value of the first element in the array
        $small_num = $biggest_num = $nums[0];

    // Iterate through the elements of the array starting from the second element
    for ($i = 1; $i < sizeof($nums); $i++)
    {
        // Update $small_num to the minimum of its current value and the current array element
        $small_num = min($small_num, $nums[$i]);
        
        // Update $biggest_num to the maximum of its current value and the current array element
        $biggest_num = max($biggest_num, $nums[$i]);
    }

    // Return the difference between the largest and smallest values in the array
    return $biggest_num - $small_num;  
 }   

// Call the 'test' function with an array [1, 5, 7, 9, 10, 12] and print the result
echo "Difference between the largest and smallest values: ". test([1, 5, 7, 9, 10, 12] );
?>