VC读写XML文件

今天对XML文件进行了一些简单的读写操作，下面来具体实现步骤：
首先：建立一个基于Dialog的MFC工程，工程名为OperateXML，然后在对话框上添加两个按钮("Create"和"GetData"和一个ListControl
控件(用来显示数据)，首先要导入库文件
#import "msxml3.dll"
using namespace MSXML2;
主要用来实现XML文件的相关操作，
双击"Create"按钮进入代码编写，代码如下：
void COperateXML::OnBtnCreate() 
{
// TODO: Add your control notification handler code here
::CoInitialize(NULL); //初始化COM
MSXML2::IXMLDOMDocumentPtr pDoc;
MSXML2::IXMLDOMElementPtr xmlRoot;
HRESULT hr = pDoc.CreateInstance(__uuidof(MSXML2::DOMDocument30));
if(!SUCCEEDED(hr))
{
   MessageBox("Error");
   return;
}
pDoc->raw_createElement((_bstr_t)(char*)"china", &xmlRoot);
pDoc->raw_appendChild(xmlRoot, NULL);
MSXML2::IXMLDOMElementPtr childNode;
pDoc->raw_createElement((_bstr_t)(char*)"city", &childNode);
childNode->Puttext("shanghai");
childNode->setAttribute("population", "7000");
childNode->setAttribute("area", "2000");
xmlRoot->appendChild(childNode);
pDoc->raw_createElement((_bstr_t)(char*)"city", &childNode);
childNode->Puttext("beijing");
childNode->setAttribute("population", "39999");
childNode->setAttribute("area", "3322");
xmlRoot->appendChild(childNode);
pDoc->save("D:\\test.xml");
}
双击"GetData"按钮进入代码编写，代码如下：
void COperateXML::OnBtnGet() 
{
// TODO: Add your control notification handler code here
m_list.DeleteAllItems();
MSXML2::IXMLDOMDocumentPtr pDoc;
HRESULT hr = pDoc.CreateInstance(__uuidof(MSXML2::DOMDocument30));
if(!SUCCEEDED(hr))
{
   MessageBox("Error!");
   return;
}
pDoc->load("D:\\test.xml");
MSXML2::IXMLDOMElementPtr childNode;
childNode = (MSXML2::IXMLDOMElementPtr)(pDoc->selectSingleNode("//city"));
MSXML2::DOMNodeType nodeType;
childNode->get_nodeType(&nodeType);
MSXML2::IXMLDOMNamedNodeMapPtr pAttrs = NULL;
MSXML2::IXMLDOMNode