Article Pagination

I need an article pagination button showing the number of pages and a Previous and Next button to navigate.
Could anyone tell me if the code below would solve my problem?
Which PHP file should I add the code?

add_filter('wp_link_pages_args', 'wp_link_pages_args_prevnext_add');

function wp_link_pages_args_prevnext_add($args)
{
    global $page, $numpages, $more, $pagenow;

    if (!$args['next_or_number'] == 'next_and_number')
        return $args; # exit early

    $args['next_or_number'] = 'number'; # keep numbering for the main part
    if (!$more)
        return $args; # exit early

    if($page-1) # there is a previous page
        $args['before'] .= _wp_link_page($page-1)
            . $args['link_before']. $args['previouspagelink'] . $args['link_after'] . ''
        ;

    if ($page<$numpages) # there is a next page
        $args['after'] = _wp_link_page($page+1)
            . $args['link_before'] . $args['nextpagelink'] . $args['link_after'] . ''
            . $args['after']
        ;

    return $args;
}

function wp_link_pages( $args = '' ) {
	$defaults = (array(
    'before' => '<p>' . __('Pages:'),
    'after' => '</p>',
    'next_or_number' => 'next_and_number', # activate parameter overloading
    'nextpagelink' => __('Next'),
    'previouspagelink' => __('Previous'),
    'pagelink' => '%',
    'echo' => 1 )
);