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Article ID: 316317 - Last Review: June 28, 2003 - Revision: 2.0
PRB: Compiler Errors When You Use #import with XML in Visual C++ .NET
This article was previously published under Q316317
SYMPTOMS
When you use MSXML parser dynamic-link libraries (DLLs)
such as Msxml.dll, Msxml2.dll, Msxml3.dll, or Msxml4.dll to compile a Visual
C++ .NET project with
#import, you may receive the following compiler error messages:
c:\sample\test.cpp(12) : error C2872:
'IXMLDOMDocumentPtr' : ambiguous symbol
could be 'c:\Program
Files\Microsoft Visual Studio .NET\Vc7\include\comdefsp.h(1228) :
_com_ptr_t<_IIID> IXMLDOMDocumentPtr' with [
_IIID=_com_IIID<IXMLDOMDocument,&
_GUID_2933bf81_7b36_11d2_b20e_00c04f983e60> ]
or
'c:\sample\Debug\msxml3.tlh(226) : MSXML2::IXMLDOMDocumentPtr'
-or-
c:\sample\test.cpp(16) : error C2039: 'async'
: is not a member of 'IXMLDOMDocument' c:\Program Files\Microsoft Visual Studio
.NET\Vc7\PlatformSDK\Include\MsXml.h(1845) : see declaration of
'IXMLDOMDocument'
-or-
c:\sample\test.cpp(27) : error C2660: 'IXMLDOMDocument::load' : function does
not take 1 parameters
You may also see other C2039 and C2660 errors
in the output. The workaround that is described in the following Knowledge Base
article does not resolve the compiler errors with Microsoft Visual C++ .NET:
269194Â
(http://kbalertz.com/Feedback.aspx?kbNumber=269194/EN-US/
)
PRB: Compiler Errors When You Use #import with XML
CAUSE
The "ambiguous symbol" error occurs when a smart pointer
interface definition such as
IXMLDOMDocumentPtr is defined in both the MSXML2 namespace (through
#import) and the global namespace (through Msxml.h), so that the symbol
is ambiguous. When the compiler resolves the interfaces, the compiler looks
first in Msxml.h, which has different signatures than those that
#import generates.
RESOLUTION
To resolve this problem, use the "typelib" namespace with
MSXML parser DLLs to prefix the interface pointers and globally unique
identifiers (GUIDs). To avoid the errors, explicitly qualify the interface
declaration and GUIDs to remove the ambiguity, as follows:
#include <stdio.h>
#import <msxml4.dll>
void dump_com_error(_com_error &e);
int main(int argc, char* argv[])
{
CoInitialize(NULL);
try
{
MSXML2::IXMLDOMDocumentPtr pXMLDoc = NULL;
HRESULT hr = pXMLDoc.CreateInstance(__uuidof(MSXML2::DOMDocument40));
pXMLDoc->async = VARIANT_FALSE; // default - true,
hr = pXMLDoc->loadXML("<tag1>Abcdef</tag1>");
//hr = pXMLDoc->load("myData.xml");
if (hr != VARIANT_TRUE)
{
MSXML2::IXMLDOMParseErrorPtr pError;
pError = pXMLDoc->parseError;
_bstr_t parseError =_bstr_t("At line ")+ _bstr_t(pError->Getline()) + _bstr_t("\n")+ _bstr_t(pError->Getreason());
MessageBox(NULL,parseError, "Parse Error",MB_OK);
return 0;
}
else
{
MessageBox(NULL,pXMLDoc->xml, "Loading Succeeded",MB_OK);
}
}
catch(_com_error &e)
{
dump_com_error(e);
}
return 0;
}
void dump_com_error(_com_error &e)
{
printf("Error\n");
printf("\a\tCode = %08lx\n", e.Error());
printf("\a\tCode meaning = %s", e.ErrorMessage());
_bstr_t bstrSource(e.Source());
_bstr_t bstrDescription(e.Description());
printf("\a\tSource = %s\n", (LPCSTR) bstrSource);
printf("\a\tDescription = %s\n", (LPCSTR) bstrDescription);
}
: Msxml.dll uses the "MSXML" namespace. Msxml2.dll, Msxml3.dll and
Msxml4.dll use the "MSXML2" namespace.
STATUS
This behavior is by design.
MORE INFORMATION
The following is a typical code sample that shows the use
of the MSXML parser with Visual C++:
#import "c:\winnt\system32\msxml4.dll"
using namespace MSXML2;
int main(int argc, char* argv[])
{
IXMLDOMDocumentPtr dom(__uuidof(DOMDocument40));
The
#import feature includes a file named Comdef.h that indirectly includes
Urlmon.h, which in turn includes Msxml.h. This is necessary because the end of
Comdef.h includes Comdefsp.h, which defines many common GUIDs and XML
interfaces. For example, the following sample causes Msxml.h to be included
before the .tlh file:
_COM_SMARTPTR_TYPEDEF(IXMLDocument, __uuidof(IXMLDocument));
_COM_SMARTPTR_TYPEDEF(IXMLElement, __uuidof(IXMLElement));
_COM_SMARTPTR_TYPEDEF(IXMLElementCollection, __uuidof(IXMLElementCollection));
_COM_SMARTPTR_TYPEDEF(IXMLElementNotificationSink, __uuidof(IXMLElementNotificationSink));
_COM_SMARTPTR_TYPEDEF(IXMLError, __uuidof(IXMLError));
With the MSXML 4.0 parser file, the Msxml4.tlh file is generated from
#import.
APPLIES TO
- Microsoft XML Parser 2.0
- Microsoft XML Parser 2.5
- Microsoft XML Parser 2.6
- Microsoft XML Parser 3.0
- Microsoft XML Core Services 4.0
- Microsoft Visual C++ .NET 2002 Standard Edition
- Microsoft Visual C++ .NET 2003 Standard Edition
| kbprb kbmsxmlnosweep KB316317 |
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