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How to find the name for interfaces implemented by a COM object

, 2 Apr 2002
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The article descibes how can you find the interfaces implemented by a COM object


This is a class that helps you to find the interfaces implemented by a COM object. Here's how you can use that MsgBox method

QI::MsgBox( yourCOMObject ); 

Code Listing

#include <atlbase.h>
#include <string>
#include <sstream>
class QI : protected CRegKey,
#ifdef _UNICODE
    public std::wstringstream
    public std::stringstream
    virtual tstring Query( IUnknown* pUnk )
        if ( pUnk != NULL && ( ERROR_SUCCESS == 
            Open( HKEY_CLASSES_ROOT, _T("Interface") ) ) )
            TCHAR szKeyName[1024] = _T("");
            for ( int i = 0; ERROR_SUCCESS == 
                RegEnumKey( m_hKey, i, szKeyName, 1024 ); i++ )
                CLSID clsID = CLSID_NULL;
                if ( SUCCEEDED( CLSIDFromString( T2OLE(szKeyName), 
                    &clsID ) ) )
                    CComPtr<IUnknown> spObject = NULL;
                    if ( SUCCEEDED( pUnk->QueryInterface( clsID, 
                        (void**)&spObject ) ) )
                        TCHAR szValue[1024] = _T(""); 
                        LONG ncbValue = 1024;
                        if ( ERROR_SUCCESS == RegQueryValue( m_hKey, 
                            szKeyName, szValue, &ncbValue ) )
                            *this << tstring(szValue) + _T("\r\n");
        return str();

    static void MsgBox( IUnknown* pUnk )
        QI objQI;
        MessageBox( NULL, objQI.Query( pUnk ).c_str(),
            _T("The object implements:"), MB_ICONINFORMATION );


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Comments and Discussions

GeneralMy vote of 1 Pinmembertha_specializt10-Jan-14 12:55 
GeneralExcellent Utility - Small and Cute PinmemberSharjith2-Apr-09 18:52 
GeneralCan't query clsid's PinmemberRené Greiner8-Apr-02 3:42 
GeneralRe: Can't query clsid's PinmemberMikelangelo8-Apr-02 8:21 
GeneralRe: Can't query clsid's PinmemberRené Greiner9-Apr-02 23:39 
I don't think that IIDFromString gets the list of interfaces but I know that QueryInterface shouldn't be used with clsids like you use it!
You have to use IIDs, which are being asked by using IIDFromString, and not CLSIDFromString !
GeneralRe: Can't query clsid's PinmemberMikelangelo9-Apr-02 23:44 
GeneralRe: Can't query clsid's PinmemberMikelangelo9-Apr-02 23:51 
GeneralRe: Can't query clsid's PinmemberRené Greiner10-Apr-02 0:01 

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