Preprocessing out function calls

[PoorLuzer]

Hi,

I want to define a macro such that, when defined, it would be able to comment out a function (specially invocation - but then all for declaration, definition and invocation would be nice)

For example,

DIAG(a, b, c);

would get transformed to:

/* DIAG(a, b, c); */ (unlikely)

or

/* DIAG(a, b, c); */;

or

/* DIAG(a, b, c) */;

.. etc

The problem is, all C comments are replaced with single spaces by the preprocessor. (AFAIK - am I wrong?)

Any ideas? The main point is to avoid the function invocations in certain runs rather than avoiding executing the body of the function (in that case, putting a return befor the first expression would have sufficed)

[quzah]

You would be better off wrapping the contents of the function in #ifndef wrappings:

void foo( ... )
{
#ifndef BAZ
    ... function body here ...
#endif
}

Naturally this prevents the use of it with standard library functions.

Quzah.

[matsp]

I'm pretty sure you can't comment the function out as such.

The common way to solve this problem is something like this:

// Set WANT_DIAG to 1 when you want diagnostic output.
#define WANT_DIAG 0

#if WANT_DIAG
#define DIAG(a, b, c)   ACTUAL_DIAG(a, b, c)
#else
#define DIAG(a, b, c)
#endif

...
#if WANT_DIAG
void ACTUAL_DIAG(int a, char *b, float c)
{
   .... // diagnostic code 
}
#endif
...
int main()
{
...
   DIAG(11, "In main", 0.3);
...

--
Mats

[anon]

Can't you do something like this?

//#define DEBUG
#include <stdio.h>

#ifdef DEBUG
#define DIAGNOSE_CALL(x) x
#else
#define DIAGNOSE_CALL(x) (void*)0
#endif

int main(void)
{
    int a = 42;
    DIAGNOSE_CALL(printf("[Conditionally printed] a = %d\n", a));
    printf("[Always printed] a = %d\n", a);
    return 0;
}