php:get description

functions.php

/**
 * [get_desc get a simple description of a long content]
 * @param  [str]  $str
 * @param  integer $len [the length you want to cut,default 50]
 * @return [string]      [Result after cutting]
 */
function get_desc($str,$len = 50){
    $str = strip_tags($str);
    if (strlen($str) < $len) {
        return $str;
    }
    $str = mb_substr(trim($str),0,$len - 3,'UTF-8');
    $num = strrpos($str, ' ');
    $str = rtrim(substr($str,0,$num));

    return preg_replace("/[\W]{1,4}$/","",$str)."...";
}