如何将$params数组作为参数传递给函数?

如何将函数中各种类型参数的数组转换为实际参数?

$params = array( 'the title2', 'the footer2', 10);
displayTest(implode(',', $params)); //how???
displayTest(convert_to_parameters($params)); //how???

function displayTest($title, $footer, $numberOfItems = 0) {
    $r = '';
    $r .= '<div>'.$title.'</div>';
    for($index = 0; $index < $numberOfItems; $index++) {
        $r .= '<div>the text</div>';
    }
    $r .= '<div>'.$footer.'</div>';
    return $r;
}