gistfile1.cpp

// enum.cpp : Defines the entry point for the console application.
//

#include "stdafx.h"
#include <cstdio>
#include <cstring>
#include <windows.h>
#include <comcat.h>

int _tmain(int argc, _TCHAR* argv[])
{
  //Initialise COM libraries
  CoInitialize (NULL);

  //The Component Category Manager implemented by System implements 
  //this interface
  ICatInformation *pCatInfo=NULL;

  //Create an instance of standard Component Category Manager
  HRESULT hr=CoCreateInstance (CLSID_StdComponentCategoriesMgr ,
			       NULL,
			       CLSCTX_INPROC_SERVER,
			       IID_ICatInformation ,
			       (void **)&pCatInfo);

  //Increase ref count on interface
  pCatInfo->AddRef ();

  //IEnumGUID interface provides enumerator for enumerating through 
  //the collection of COM objects
  IEnumGUID *pEnumGUID=NULL;

  //We are intersted in finding out only controls so put CATID_Control 
  //in the array
  CATID pcatidImpl[1];
  CATID pcatidReqd[1];
  pcatidImpl[0]=CATID_Control;

  //Now enumerate the classes i.e. COM objects of this type.
  pCatInfo->EnumClassesOfCategories (1,
				     pcatidImpl,
				     0,
				     pcatidReqd ,
				     &pEnumGUID);

  //Enumerate as long as you get S_OK
  CLSID clsid;

  while( (hr= pEnumGUID->Next( 1, &clsid, NULL ))==S_OK )
    {
      BSTR bstrClassName;   //Get the information of class

      //This is what MSDN says about the parameters
      /*-----------------------------------------------
	USERCLASSTYPE_FULL     The full type name of the class. 
	USERCLASSTYPE_SHORT    A short name (maximum of 15 characters) that 
	is used for popup menus and the Links dialog 
	box. 
	USERCLASSTYPE_APPNAME  The name of the application servicing the class 
	and is used in the Result text in dialog boxes. 
	-----------------------------------------------*/
      OleRegGetUserType (clsid,USERCLASSTYPE_FULL,&bstrClassName);
      printf("%S\n", bstrClassName);
      //Add string in our listbox
    }          

  //we are done so now release the interface ptr
  pCatInfo->Release ();

  CoUninitialize ();
}