It's also very interesting that you can do FANCY stuff using function-like macros
Code:
#define MIN(%1,%2) ( ((%1) < (%2)) ? (%1) : (%2))
MIN(5, 6) evaluates to:
( ( (5) < (6) ) ? (5) : (6) )
(damn, I can't see whether I've got enough parenthesis even with those spaces!!)
Thus evaluating to 5.
Of course, HARDCORE C Programmers notice immediately: THIS IS TEH SHIT because if you pass ++i, ++i will appear twice in the preprocessor output, thus i will be incremented twice if one of the code paths is taken and only once if the other one is taken. That's why you might want to always mark function-like preprocessor macro using CAPS LOCK (or by holding shift while writing the macro name).
Greetings,
PM