Joins an array of strings into a comma-separated string of readable output.

CommaSeparatedList.php

<?php

/**
 * Joins an array of strings into a comma-separated string of readable output.
 * Array ['John', 'Paul', 'George', 'Ringo'] becomes the string "John, Paul, George, and Ringo".
 *
 * @param array $items
 * @param bool|true $oxfordComma
 * @param string $conjunction
 * @return string
 */
function commaSeparatedList($items, $conjunction = 'and', $oxfordComma = true)
{
    if (count($items) === 1) {
        // The array has only one item, so just return it since it's the entire list.
        return array_pop($items);
    }

    // Set up the Oxford comma with a space, if it's even needed.
    $oxfordComma = ($oxfordComma && count($items) > 2 ? ', ' : ' ');

    // Remove the last item so we can interject an Oxford comma as necessary
    $lastItem = array_pop($items);

    return implode($items, ', ') . $oxfordComma . $conjunction . ' ' . $lastItem;
}