php函数：判断字符编码的简单方法

3. function chkbm($string){
4.     $bm = array(ASCII, GBK, UTF-8);
6.     foreach($bm as $c){
7.         if( $string === iconv(UTF-8, $c, iconv($c, UTF-8, $string))){//转换编码后是不是相等
8.             return $c;
9.         }
10.     }
11.     return null;
12. }
13. ?>