/**
*  将数组转换为xml
*  @param array $data  要转换的数组
*  @param bool $root   是否要根节点
*  @return string     xml字符串
*  @author Dragondean
*  @url  http://www.cnblogs.com/dragondean
*/
function arr2xml($data, $root = true){
  $str="";
  if($root)$str .= "<xml>";
  foreach($data as $key => $val){
    if(is_array($val)){
      $child = arr2xml($val, false);
      $str .= "<$key>$child</$key>";
    }else{
      $str.= "<$key><![CDATA[$val]]></$key>";
    }
  }
  if($root)$str .= "</xml>";
  return $str;
}