Compare a string and an array and return the common elements as a string.

pis_compare_string_to_array.php

<?php

/**
 * Compare a string and an array and return the common elements as a string.
 *
 * @param string $string The string to be compared.
 * @param array  $array  The array to be compared.
 *
 * @return string $output The string containing the common values.
 *
 * @since 3.8.8
 */
function pis_compare_string_to_array($string = '', $array = array())
{
    // Convert the string to lowercase
    $string = strtolower($string);
    // Remove any space from the string
    $string = str_replace(' ', '', $string);
    // Remove any comma at the beginning and at the end of the string
    $string = trim($string, ', ');
    // Convert the string into an array
    $string = explode(',', $string);

    // Compare the two arrays and return the intersection (the common values)
    $output = array_intersect($string, $array);
    // Convert the returned array into a string
    $output = implode(', ', $output);

    return $output;
}