PHP 字符串转为UTF8编码

---

function str2UTF8($str)
{
    $encode = mb_detect_encoding($str, ['ASCII', 'UTF-8', "GB2312", "GBK", 'BIG5']);

    if($encode == 'UTF-8')
    {
        return $str;
    }
    else
    {
        return mb_convert_encoding($str, 'UTF-8', $encode);
    }
}