MSXML insertBefore(IXMLDOMNode *newChild, VARIANT refChild) 传参

在xml操作中经常会用到在某一个节点后或前面插入一个节点，MSXML DOM 中使用的函数是insertBefore(IXMLDOMNode *newChild, VARIANT refChild)；第二个参数只的是参考节点的内存地址传参需要用到 _variant_t 的 IDispatch构造方法，代码如下


#import "msxml3.dll" rename_namespace("MSXML")

void InsertDemo() {

    CComPtr<MSXML::IXMLDOMDocument> pDoc;

    pDoc.CoCreateInstance(__uuidof(MSXML::DOMDocument));

    pDoc->load(_variant_t("xxx.xml"));

    CComPtr<MSXML::IXMLDOMElement> pRoot = pDoc->GetdocumentElement();

    CComPtr<MSXML::IXMLDOMNodeList> nodeList = pRoot->GetchildNodes();

    /*创建新节点*/

    CComPtr<MSXML::IXMLDOMElement> newElement = pDoc->createElement(_bstr_t("newNode"));

    newElement->setAttribute(_bstr_t("key"), _variant_t("value"));

    /*在第三个节点前插入新节点*/

    CComPtr<MSXML::IXMLDOMNode> refNode = nodeList->Getitem(2);

    pRoot->insertBefore(newElement, _variant_t((IDispatch*)refNode));

    pDoc->save(_variant_t("xxx.xml"));

}