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        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&&$asc    if($asc>=-20283&&$asc    if($asc>=-19775&&$asc    if($asc>=-19218&&$asc    if($asc>=-18710&&$asc    if($asc>=-18526&&$asc    if($asc>=-18239&&$asc    if($asc>=-17922&&$asc    if($asc>=-17417&&$asc    if($asc>=-16474&&$asc    if($asc>=-16212&&$asc    if($asc>=-15640&&$asc    if($asc>=-15165&&$asc    if($asc>=-14922&&$asc    if($asc>=-14914&&$asc    if($asc>=-14630&&$asc    if($asc>=-14149&&$asc    if($asc>=-14090&&$asc    if($asc>=-13318&&$asc    if($asc>=-12838&&$asc    if($asc>=-12556&&$asc    if($asc>=-11847&&$asc    if($asc>=-11055&&$asc    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);  

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