首先建立一个XML文件，我的机器软件configuration如下：

        Windows xp professional sp2

        IE 6.0( 无关紧要)

        VS 2003

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        #import <msxml3.dll> //I have no idea why msxl4 cannot be used

                        //in my PC, may be something on personal

                        //discrimination

        using namespace MSXML2;///the same to above///

-----------------------------------------------------------------------------------创建文件 

        int CreateXMLFile(char * xml_file_name)

        {  
                 // create an xml file named xml_file_name comtemporily

                // if the return val is "0",it means that creation

                // if failed

                ::CoInitialize(NULL);// this item must be included

                                //it is fatal ,else it will failed

                                //then at last “::CoUninitialize();”

                //matched

 

                MSXML2::IXMLDOMDocumentPtr pDoc;

 

                HRESULT hr = pDoc.CreateInstance(__uuidof(DOMDocument30));//         

                //<msxml3.dll> version is 3.0

 

                if(!(SUCCEEDED(hr)))//faild

                {           

                        return 0;

                }

 

                MSXML2::IXMLDOMElementPtr pPolicy=pDoc->createElement("Local"); 

                pDoc->appendChild(pPolicy); 

                { 
                         // the brackets including 1,2,3 can show the

                        //tree structure of the xml file

                        // nodes

                        //1

                        MSXML2::IXMLDOMElementPtr pPolicyType; 

 

                        pPolicyType=pDoc->createElement("North");

                        pPolicyType->Puttext("Piking");

                        pPolicy->appendChild(pPolicyType);

 

                        pPolicyType=pDoc->createElement("South");            

                        pPolicy->appendChild(pPolicyType);

                {//2.1

                        MSXML2::IXMLDOMElementPtr pControlType;

                        pControlType=pDoc->createElement("Shanghai");     

                        pControlType->Puttext("Xujiahui");

                        pPolicyType->appendChild(pControlType);

 

                        pControlType.Release();

                }//end 2.1

                        pPolicyType=pDoc->createElement("East");

                        pPolicy->appendChild(pPolicyType);   

                {//2.2

                        MSXML2::IXMLDOMElementPtr pProcessType;

                        pProcessType=pDoc->createElement("Heilongjiang");

                        pProcessType->Puttext("harbin,Qiqihar");

                        pPolicyType->appendChild(pProcessType);

 

                        pProcessType=pDoc->createElement("Liaoning");     

                        pProcessType->Puttext("ShenYang,Dalian");

                        pPolicyType->appendChild(pProcessType);

 

                        pProcessType.Release();

                }//end 2.2

                        _variant_t varXml(xml_file_name);

                        pDoc->save(varXml);    //save the file        

                        pPolicy.Release();

                        pPolicyType.Release();

                 }//end 1

                pDoc.Release();

                ::CoUninitialize();   //necessary it same as new and delete

                return 1;

 

        }

 

        产生的文件如下。。

        <Location>

        <North> Pingking</North>

        <South>

        <Shanghai>Xujiahui</Shanghai>

        </South>

        <East>

        <Heilongjiang>harbin,qiqihar</Heilongjiang>

        <Liaoning>Shenyang,Dalian</Liaoning>

        </East>

-----------------------------------------------------------------------------------------查找值

        访问结点时，如果要读<North>的值，就直接把”North”写进去，返回的就是Pingking了，

        要访问<Shanghai>要代入”South\\Shanghai”， 这个和注册表分健值很像

        char* GetValueFromXml( char* nodeName)

        {
                 // get the value of certain node named nodeName

                // from the xml file

                // the return value 0 represent failure

                char* nodeValue=NULL;

                ::CoInitialize(NULL);

                MSXML2::IXMLDOMDocumentPtr pDoc;

                HRESULT hr = pDoc.CreateInstance(__uuidof(DOMDocument30));

 

                if(!(SUCCEEDED(hr)))

                {    

                        return nodeValue;

                }  

 

                hr=pDoc->load("book.xml");

                if(!SUCCEEDED(hr))

                {           

                        MSXML2::IXMLDOMElementPtr pPolicyNode=pDoc->GetdocumentElement();           

                        MSXML2::IXMLDOMElementPtr pSelectNode=pPolicyNode->selectSingleNode(nodeName);       

                        nodeValue =    _com_util::ConvertBSTRToString(pSelectNode->text);             

                        pPolicyNode.Release();

                        pSelectNode.Release();

                }

                pDoc.Release();

                ::CoUninitialize();

                return nodeValue;

        }

--------------------------------------------------------------------------------修改XML 文件中的某一个结点的值

        访问方法同上

        int modify(const char* nodeName,char* nodeValue)//前者为结点名，后者为结点的字串值。

        {
                 // modify the value of node named as nodeName

                // the new value is nodeValue

                // if the xml file is not existed then return

                // 0

                ::CoInitialize(NULL);

                MSXML2::IXMLDOMDocumentPtr pDoc;

                HRESULT hr = pDoc.CreateInstance(__uuidof(DOMDocument30));

                int rtval=0;

                if(!(SUCCEEDED(hr)))

                {    

                        rtval=0;  

                        return rtval;

                }  

 

                hr=pDoc->load("book.xml");// 文件名。

      

                if(!SUCCEEDED(hr))

                {

                        MSXML2::IXMLDOMElementPtr pPolicyNode=pDoc->GetdocumentElement();           

                        MSXML2::IXMLDOMElementPtr 二pSelectNode=pPolicyNode->selectSingleNode(nodeName);

                        pSelectNode->Puttext(nodeValue);

                        pDoc->save("book.xml");

                        pPolicyNode.Release();

                        pSelectNode.Release();

                        rtval=1;         

                }

                pDoc.Release();

                ::CoUninitialize();

                return rtval;

        }

 

-------------------------------------------------------------------------------------------------删去结点