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

Remove the last element from the list, implode what's left with commas and then concatenate "and last_element":

$last = array_pop($number_list);
$output = implode(', ', $number_list);
if ($output) {
    $output .= ', and ';
}
$output .= $last;

If you prefer, you can also write the above more tersely as

$last = array_pop($number_list);
$output = $number_list
    ? implode(', ', $number_list).', and '.$last
    : $last;

Update:

I have to admit I initially misread the question and thought that it was about replacing the last comma with "and", not adding an "and" before the final item. I have since edited the answer to target the latter scenario. Note that the code can be easily adapted to do either by selecting " and " or ", and " for the "glue" string respectively.