Compiletime vs run time

How do I modified into runtime since #ifdef I am using is currently in compile time?


#define abc 1

#ifdef abc
static function a(){
}
#else
static function b(){
}
#endif

I think that if you use #if then you can use most of the "usual operators" however I can't seem to find much formal documentation on this.

Code:

---

#define TEST2

#if defined TEST || defined TEST2
cout << "made it here" << endl;
#endif

#if defined TEST && defined TEST2
cout << "if this works its broken" << endl;
#endif

---