Rounding in C-preprocessor

Question

I define some values ​​in the preprocessor. eg.

#define a 1000
#define b 0.5*a

When I try to use b in a place where an integer is required, I get an error. I don’t want to balways include it in my code and do it once per line #define, is this possible?

Answer 1

Try the following:

#define a 1000
#define b (a/2)

Answer 2

#define b ((int)(a * 0.5))