Limit the excerpt lenght without truncating words

functions.php

/**
 * ----------------------------------------------------------------------------
 * LIMITAR EXCERPT
 * Limita o excerpt sem cortar palavras a meio
 * http://wordpress.stackexchange.com/questions/70913/how-can-i-limit-the-character-length-in-excerpt
 * ----------------------------------------------------------------------------
 */

function get_excerpt($limit, $source = null){

    if($source == "content" ? ($excerpt = get_the_content()) : ($excerpt = get_the_excerpt()));
    $excerpt = preg_replace(" (\[.*?\])",'',$excerpt);
    $excerpt = strip_shortcodes($excerpt);
    $excerpt = strip_tags($excerpt);
    $excerpt = substr($excerpt, 0, $limit);
    $excerpt = substr($excerpt, 0, strripos($excerpt, " "));
    $excerpt = trim(preg_replace( '/\s+/', ' ', $excerpt));
    $excerpt = $excerpt.'... <a href="'.get_permalink($post->ID).'">more</a>';
    return $excerpt;

}