Redefine(#define) reserved c++ key word

Question

Is it possible to redefine a c++ keyword using #define?

#ifdef int
#undef int 
#define int 2
#endif
int main(){
    //Do something with int
}

I

Answer 1

Is it possible? Yes. Is it good style? Absolutely not.

The preprocessor is not aware of C/C++ keywords, it only knows about preprocessor tokens and just does strict text replacement.

Your example is resulting in an error because you're #undefing it. Once you undefine it, it reverts to its previous behavior.

The only valid use I know of for doing something like this is to work around a bug in an old compiler, and that compiler is no longer relevant these days.