function isUTF8($str){
$length=strlen($str);
for($i=0;$i<$length;$i++){
$high=ord($str{$i});
if(($high==0xC0)||($high==0xC1)){
return false;
}elseif($high<0x80){
continue;
}elseif($high<0xC0){
return false;
}elseif($high<0xE0){
if(++$i>=$length)
return true;
elseif(($str{$i}&"\xC0")=="\x80")
continue;
}elseif($high<0xF0){
if(++$i>=$length){
return true;
}elseif(($str{$i}&"\xC0")=="\x80"){
if(++$i>=$length)
return true;
elseif(($str{$i}&"\xC0")=="\x80")
continue;
}
}elseif($high<0xF5){
if(++$i>=$length){
return true;
}elseif(($str{$i}&"\xC0")=="\x80"){
if(++$i>=$length){
return true;
}elseif(($str{$i}&"\xC0")=="\x80"){
if(++$i>=$length)
return true;
elseif(($str{$i}&"\xC0")=="\x80")
continue;
}
}
}
return false;
}
return true;
}

$tmpstr = @gb2utf8($uid);

$tmpstr2 = @utf82gb($tmpstr);

if($tmpstr2==$uid) $uid = $tmpstr;

if(!isUTF8($uid)) $uid = @gb2utf8($uid);