This example shows how create a CXlOper return value from a string.

// Function:    MyUpper 
// Returns:     LPXLOPER 
// Description: Returns the input string converted to upper-case 
 
//{{XLP_SRC(MyUpper) 
    // NOTE - the FunctionWizard will add and remove mapping code here. 
    //    DO NOT EDIT what you see in these blocks of generated code! 
 
#pragma region MyUpper support code
IMPLEMENT_XLLFN4(MyUpper, MyUpper_4, MyUpper_12, "RC", "UC%", L"MyUpper", 0, 
    L"Input", 0, L"14", 0, L"Returns the input string converted to upper-case", 
    0, L"Input string\0", 0, 0, L"{MyUpper,,,Returns the input string converte"
    L"d to upper-case,14,1,128,U,{{0,{Input,String,0,,Input string,,,,}}},{},3"
    L",,0,0,,,,0,0}", 1, 0, 0)
CXlOper* MyUpper_Impl(CXlOper&, const CXlStringArg&);
extern "C" __declspec(dllexport)
LPXLOPER12 MyUpper_12(const XCHAR* Input)
{
    XLL_FIX_STATE;
    CXlOper xloResult;
    CXlStringArg Input__port(Input);
    try {
        CXlStructuredExceptionHandler _seh_;
        xloResult.HandleResult(MyUpper_Impl(xloResult, Input__port));
    }
    catch(const CXlRuntimeException& ex) {
        CXllApp::Instance()->DisplayException(xloResult, ex);
    }
    XLP_CATCH_CLR_EXCEPTIONS_TO(xloResult)
    return xloResult.Ret12();
}
extern "C" __declspec(dllexport)
LPXLOPER4 MyUpper_4(const char* Input)
{
    XLL_FIX_STATE;
    CXlOper xloResult;
    CXlStringArg Input__port(Input);
    try {
        CXlStructuredExceptionHandler _seh_;
        xloResult.HandleResult(MyUpper_Impl(xloResult, Input__port));
    }
    catch(const CXlRuntimeException& ex) {
        CXllApp::Instance()->DisplayException(xloResult, ex);
    }
    XLP_CATCH_CLR_EXCEPTIONS_TO(xloResult)
    return xloResult.Ret4();
}

#pragma endregion

CXlOper* MyUpper_Impl(CXlOper& xloResult, const CXlStringArg& Input)
{
    // End of generated code 
//}}XLP_SRC

    CString stIn(Input);
    stIn.MakeUpper();
    xloResult = stIn; 
    return xloResult.Ret();
}

Uses

CXlOper::CXlOper