Question

If I have a constant defined as such in a header file:

#define MY_CONSTANT 1

And I include a library to the whole project which includes a different definition for the same constant:

#define MY_CONSTANT 0

I naturally get conflicts while compiling. Supposing that I cannot alter my project code and that I can only change my library code, what can I do to make MY_CONSTANT as defined by my lib?

EDIT:
just to clarify, my goal is to update a constant in my code through a library. Because I’m writing a library to simulate hardware functions, I have to go by the rule that the software itself must be untouched. There is a loop of sort in the main file that uses the constant. I need to change this constant, but without actually altering it in the main file.

Answer 1

You can undefine the other definition

#ifdef MY_CONSTANT
#undef MY_CONSTANT
#endif
#define MYCONSTANT 0

Also, you should remove the =, and the ;

P.S. as mentioned, it will not change the code that already compiled.