How to define macro function which support no input parameter and support also input parametr in the same time

Question

I want to define a macro function which support at the same time:

1) No input parameter

2) Input parameters

some thing like that:

#de         


        

Answer 1

The C99 standard says,

An identifier currently defined as an object-like macro shall not be redefined by another #define reprocessing directive unless the second definition is an object-like macro definition and the two replacement lists are identical. Likewise, an identifier currently defined as a function-like macro shall not be redefined by another #define preprocessing directive unless the second definition is a function-like macro definition that has the same number and spelling of parameters, and the two replacement lists are identical.

I think compiler prompts a warning of redefined MACRO. Hence it is not possible.