Rounding in C Preprocessor -

I am defining some values ​​in the preprocessor. E.g. A 1000 #define b 0.5 * a

When I try to use b at a place where integer is required I get an error I always have my code in Do not want to enter b and do it once in the #define line, is it possible?

Try it out:

  # defined one 1000 # A / 2)