Macro as a parameter to another macro

Question

I\'m trying to pass the parameters to macro SETBIT with another predefined macro like this:

#define SETBIT(ADDRESS,BIT,N) {(N) ? (ADDRESS &=         


        

Answer 1

This works:

#define SETBIT2(ADDRESS,BIT,N) ((N) ? (ADDRESS &= ~(1<<BIT)) : (ADDRESS |= (1<<BIT)))
#define SETBIT(PARAMS) SETBIT2(PARAMS)
#define PORTB 5
#define POS 7
#define DAC_SYNC PORTB,3,POS

int main() {
  int a = SETBIT(DAC_SYNC);
  return 0;
}

Answer 2

Just for the sake of completeness, that same manual you are linking to also states:

The number of arguments you give must match the number of parameters in the macro definition. When the macro is expanded, each use of a parameter in its body is replaced by the tokens of the corresponding argument.

So ooga's example is a nice demonstration of how macro expansion works recursively, first the outer macro gets expanded, then the argument.