访问 XML 结构中的属性值 - 使用 MSXML6 的 C++

问：

我在下面有这个XML文件：

<catalog>   
  <book id="bk101">
    <author> Gambardella, Matthew </author>
    <title>XML Developer's Guide</title>
    <genre>Computer</genre>
    <price>44.95</price>
    <publish_date>2000-10-01</publish_date>
    <description>An in-depth look at creating applications with XML.</description>
  </book>
</catalog> 

我想在节点内打印属性（即 的值，即 ），但是我在使用 MSXML6 库时遇到麻烦，我想坚持使用它而不是更改为 Rapid 等。bookidbk101

以下是我到目前为止的代码：

#include <stdio.h>
#include <tchar.h>
#include <windows.h>
#import <msxml6.dll> rename_namespace(_T("MSXML"))
#include<iostream>
#include<string>

int main(int argc, char* argv[]) {
    HRESULT hr = CoInitialize(NULL);
    if (SUCCEEDED(hr)) {
        try {
            MSXML::IXMLDOMDocument2Ptr xmlDoc;
            MSXML::IXMLDOMNodePtr bookholder;
            MSXML::IXMLDOMNodePtr author;
            MSXML::IXMLDOMNodePtr title;
            
            hr = xmlDoc.CreateInstance(__uuidof(MSXML::DOMDocument60),
                NULL, CLSCTX_INPROC_SERVER);
            // TODO: if (FAILED(hr))...
            
            if (xmlDoc->load(_T("books.xml")) != VARIANT_TRUE) {
                printf("Unable to load input.xml\n");
            }
            else {
                printf("XML was successfully loaded\n");

                xmlDoc->setProperty("SelectionLanguage", "XPath");
                MSXML::IXMLDOMNodeListPtr booklist = xmlDoc->selectNodes("/catalog/*");
                bookholder = booklist->Getitem(0);
                //printf(bookholder->Getxml()+"\n"); //works till here
                //printf(bookholder->; //what to do here to print attribute?
            }
        }
        catch (_com_error& e) {
            printf("ERROR: %ws\n", e.ErrorMessage());
        }
        CoUninitialize();
    }
    return 0;
}