中文英文字符串截取 指定个数

public static function arr_split_zh($tempaddtext)
{
    $tempaddtext = iconv("UTF-8", "gb2312", $tempaddtext);
    $cind = 0;
    $arr_cont = [];

    for($i = 0; $i < strlen($tempaddtext); $i++){
        if (strlen(substr($tempaddtext, $cind, 1)) > 0){
            if (ord(substr($tempaddtext, $cind, 1)) < 0xA1){ //如果为英文则取1个字节
                array_push($arr_cont, substr($tempaddtext, $cind, 1));
                $cind++;
            }else{
                array_push($arr_cont, substr($tempaddtext, $cind, 2));
                $cind += 2;
            }
        }
    }
    foreach($arr_cont as &$row){
        $row = iconv("gb2312", "UTF-8", $row);
    }

    return $arr_cont;

}

$array = self::arr_split_zh($content);
if (count($array) <= 54){
    return $content;
}else{
    $str = implode('', array_slice($array, 0, 54));
    return $str;
}