Comma separated list from array with “and” before last element

Question

I have an array ($number_list) that has a dynamically generated list of values. There will be at least 1 value in the array and no more than 4.

Currentl

Answer 1

$number_list = array(4, 5, 6, 7);    
$comma_list = strrev(implode(strrev(', and'), explode(strrev(','), strrev(implode(', ', $number_list)), 2)));
echo 'The list is ' . $comma_list . '.';

Output: The list is 4, 5, 6, and 7.