Determination declension words

declension_ru.php

<?php
    function declension($num, $words)
    {
        $num = $num % 100;
        if ($num > 19) {
            $num = $num % 10;
        }
        switch ($num) {
            case 1: {
                return($words[0]);
            }
            case 2: case 3: case 4: {
                return($words[1]);
            }
            default: {
                return($words[2]);
            }
        }
    }
?>