php 解析字符串編碼方式 GB2312 UTF8

//查看編碼方式
$codeFormat = mb_detect_encoding($inStr, array("ASCII", "UTF-8", "GB2312", "GBK", "BIG5"));
echo $codeFormat;

//轉碼
if ($codeFormat == "UTF-8")
{
    $outStr = iconv("UTF-8", "GBK", $inStr);
}