Thread: Using switch statements in function-like macros

Maybe someone out there can help me understand my problem. I'm trying to use a switch statement in a function-like macro, but I keep getting the following error:

error: expected expression before ‘switch’

Here's some example code of what I'm doing. It's not fancy but I'm just trying to get the concept down:

Code:

#include <stdio.h>
#include <stdlib.h>

#define MACRO_SUCCESS 1
#define MACRO_FAILURE 0

#define check_error(error) \
( switch (error) \
  {              \
    case 1:  return MACRO_SUCCESS;  \
    case 2:  return MACRO_FAILURE;  \
  }              \
)


int main (int argc, char *argv[])
{
	printf("error flag = %d\n\r", check_error(2));
	printf("error flag = %d\n\r", check_error(1));
	
	return 0;
}

You can't put a switch statement inside a printf statement. (Remember that macros just do plain old text substitution.) You can use a real function if you want. If for some pedagogical reason you are required to use a macro, you can use ?: in this case.

or maybe u could do something like this:

Code:

#define MACRO_SUCCESS 1
#define MACRO_FAILURE 0

#define check_error2(error) int flag; \
switch (error)    \
{ \
case 1: {flag = MACRO_SUCCESS; break; } \
case 2: { flag = MACRO_FAILURE; break; }   \
} \


int y = 1;

check_error2(y)


printf("error flag = %d\n", flag);