Accessing attribute values in an XML structure- C++ using MSXML6

Question

I have this XML file below:

<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> 

I would like to print the attribute inside the book node (that being the value of id, which is bk101), however I'm having trouble using the MSXML6 library to do so, and I would like to stick with it instead of changing to Rapid, etc.

Below is my code so far:

#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;
}