Limit Text Content

/**
* Limit words of a content
* $post_id: pass the post id
* $limit: int ( default 50 )
* use: get_intro_text ( get_the_ID(), 100 );
*/

function get_intro_text( $post_id, $limit = 50 )
{
    $intro_text = get_the_content($post_id);

    $intro_text = preg_replace(" ([.*?])",'',$intro_text);

    $intro_text = strip_shortcodes($intro_text);
    $intro_text = strip_tags($intro_text);
    $intro_text = substr($intro_text, 0, $limit);
    $intro_text = substr($intro_text, 0, strripos($intro_text, " "));
    $intro_text = trim(preg_replace( '/\s+/', ' ', $intro_text));
    $intro_text = $intro_text.'... <a href="'.get_the_permalink( $post_id ).'">read more</a>';
    return $intro_text;
}