Question

Can I define a macro like:

#define ERROR_REPORT(LEVEL,SUB_LEVEL printf(

Compiler complain this line expecting a ;. Is there a way to escape the “(“?

This is intended to replace a function:

  ERROR_REPORT(LEVEL,SUB_LEVEL
          "error, there is an error %d\n",
           error_id);

with a C built-in function

  printf("error, there is an error %d\n",
         error_id);

EDIT: I just want to replace one “(“, not include “)”. The reason why I ask this is that there are already some codes as posted in question, so I just want to replace one line like ERROR_REPROT(… with printf( .

Answer 1

I suggest you use variadic macros:

#define ERROR_REPORT(LEVEL, SUB_LEVEL, ...) \
    printf(__VA_ARGS__)

While you can put whatever you want as the replacement for a macro, you define it wrong:

#define ERROR_REPORT(LEVEL,SUB_LEVEL   printf(
/*      Error with missing `)` here ^ */

The preprocessor needs the closing parenthesis, or it will cause errors in the preprocessing phase.

Also when you are using this macro you can’t do as you do:

ERROR_REPORT(LEVEL,SUB_LEVEL
      "error, there is an error %d\n",
       error_id);

The preprocessor will throw an error here too as there is no comma between the SUB_LEVEL argument and the string.

So the answer to the question if you can replace a single left parenthesis is simply no, you can’t.