HOW TO: Is there a way to reproduce the way Excel returns errors?

Is there a way to reproduce the way Excel returns errors?

Question

Is there anyway to reproduce the way Excel returns errors? I can return a string with an error, such as "#VALUE!" but it is not formatted like an Excel error.

Answer

Return a CXlOper that contains an error code, such as xlerrValue, xlerrNA etc. You could return #VALUE! as follows:

CXlOper xloResult; 
xloResult = xlerrValue;
return xloResult.Ret();

You can also use a short-cut to return an error code, without instantiating a CXlOper to put it in, using the static method CXlOper::RetError(), thus:

return CXlOper::RetError(xlerrValue);

This technique is useful for a concise early exit from an add-in function, e.g.:

if (x < 0)
    return CXlOper::RetError(xlerrValue);
else if (x == 0)
    return CXlOper::RetError(xlerrDiv0);
// Continue with normal processing
...

See Also

• Error Codes contains a list of the various error codes that can be returned from an add-in function.
• CXlOper::RetError() documentation.