This example shows how to optionally return an error.
// Function: MySqrt // Returns: LPXLOPER // Description: Returns the square root of the input //{{XLP_SRC(MySqrt) // NOTE - the FunctionWizard will add and remove mapping code here. // DO NOT EDIT what you see in these blocks of generated code! IMPLEMENT_XLLFN2(MySqrt, "RB", "MySqrt", "Input", "User Defined", "Returns the square root of the input", "Number whose square " "root is to be returned\000", "\0", 1) extern "C" __declspec( dllexport ) LPXLOPER MySqrt(double dInput) { CXlOper xloResult; //}}XLP_SRC if ( dInput > 0.0 ) xloResult = sqrt(dInput); else xloResult = (WORD)(-dInput); return xloResult.Ret(); }