php实现过滤字符串中的中文和数字实例

function getChinese($string,$encode="GBK") {  switch($encode){   case "GBK" :$codelength=2;break;   case "GB2312" :$codelength=3;break;   case "UTF-8" :$codelength=3;break;   case "UTF-16" :$codelength=4;break;  }  $tmpstr = '';  $arr = array(1,2,3,4,5,6,7,8,9,0);  $strlen = strlen($string);  for($i=0; $i<$strlen; $i++) {   $str=substr($string, $i, 1);   $str1=trim($str);   if( ord($str)>0xA0 ){   $tmpstr.= substr($string, $i, $codelength);   $i = $i+$codelength-1;   }  } return $tmpstr;}