php获取汉字首字母并排序出现大量NOTIC错误，大神

function getFirstChar($str){
if(empty($str)){
return '';
}
$fchar=ord($str{0});
if($fchar>=ord('A')&&$fchar<=ord('z')){
return strtoupper($str{0});
}
$s1 = iconv('UTF-8', 'GB18030',$str);
$s2 = iconv('GB18030','UTF-8',$s1);
$s=$s2==$str?$s1:$str;
$asc=ord($s{0})*256+ord($s{1})-65536;
if($asc>=-20319&&$asc<=-20284) return 'A';
if($asc>=-20283&&$asc<=-19776) return 'B';
if($asc>=-19775&&$asc<=-19219) return 'C';
if($asc>=-19218&&$asc<=-18711) return 'D';
if($asc>=-18710&&$asc<=-18527) return 'E';
if($asc>=-18526&&$asc<=-18240) return 'F';
if($asc>=-18239&&$asc<=-17923) return 'G';
if($asc>=-17922&&$asc<=-17418) return 'H';
if($asc>=-17417&&$asc<=-16475) return 'J';
if($asc>=-16474&&$asc<=-16213) return 'K';
if($asc>=-16212&&$asc<=-15641) return 'L';
if($asc>=-15640&&$asc<=-15166) return 'M';
if($asc>=-15165&&$asc<=-14923) return 'N';
if($asc>=-14922&&$asc<=-14915) return 'O';
if($asc>=-14914&&$asc<=-14631) return 'P';
if($asc>=-14630&&$asc<=-14150) return 'Q';
if($asc>=-14149&&$asc<=-14091) return 'R';
if($asc>=-14090&&$asc<=-13319) return 'S';
if($asc>=-13318&&$asc<=-12839) return 'T';
if($asc>=-12838&&$asc<=-12557) return 'W';
if($asc>=-12556&&$asc<=-11848) return 'X';
if($asc>=-11847&&$asc<=-11056) return 'Y';
if($asc>=-11055&&$asc<=-10247) return 'Z';
return null;
}


NOTIC: [8] iconv(): Detected an illegal character in input string D:\develop\upupw\htdocs\shixiapi\App\Common\Common\function.php 第 1157 行.
NOTIC: [8] iconv(): Detected an illegal character in input string D:\develop\upupw\htdocs\shixiapi\App\Common\Common\function.php 第 1157 行.
NOTIC: [8] iconv(): Detected an illegal character in input string D:\develop\upupw\htdocs\shixiapi\App\Common\Common\function.php 第 1157 行.

回复讨论(解决方案)

简单点就

$s1 = @iconv('UTF-8', 'GB18030',$str);$s2 = @iconv('GB18030','UTF-8',$s1);  

规矩点就

$s = mb_check_encoding($str, 'utf-8') ? iconv('utf-8', 'gbk', $str) : $str;

GB18030 标准虽然发布，但尚未在任何系统中实现