Since I'm in the Linux world at my new job, I'm a bit rusty myself. I do find that using the T-functions (along with classes that can use both char* and wchar_t*) alleviates much of those headaches. If you decide to become a software engineer, you are signing up to have a 1/2" piece of silicon tell you exactly how stupid you really are for 8 hours a day, 5 days a week Zac

I don't think so because I experimented with the fresh ATL project, by adding only 3 lines of extra code of file operation consists of "fopen, fprintf and fclose". Here also I have found that "fprintf" is posing same problem. Please you can easily check it by creating simple ATL dll with a method consists of these file operation lines. And we should use that method in C#. It 'll definately throw the same error. Regards, Arun

At a minimum: FILE *sLogFile = fopen("XMPLog.txt", "wb"); if (sLogFile != NULL) { fprintf(sLogFile, "Version : %s\n", version.message.c_str()); fclose(sLogFile); } else MessageBox(...); "The largest fire starts but with the smallest spark." - David Crow "Judge not by the eye but by the heart." - Native American Proverb

IDL defenition will be: [id(1), helpstring("your atl method signature")] HRESULT YourATLMethod( [out,retval] BSTR* ReturnString); and the C++ implimentation signature will be: STDMETHODIMP CYourClass::YourATLMethod(BSTR* ReturnString) { _bstr_t bstrReturnstring = _T("some string here"); *ReturnString = bstrReturnstring ; return S_OK; } cheers..milton kb.

Use the below signature for the COM method. Then use RCW to call this method from .Net [id(1)] HRESULT ReturnString([in,out] BSTR stringValue); cheers....MIlton KB

STDMETHODIMP CYourClass::YourATLMethod(BSTR Filepath, BSTR* ReturnString) { use the BSTR FilePath to get the BSTR to return, you can also use a LPCOLESTR CComBSTR TheReturnString = L"the string"; *ReturnString = SysAllocString(TheReturString.m_str); //or any BSTR or LPCOLESTR to be allocated by the system using the pointer given by the com client return S_OK; }