#ifdef vs #if - which is better/safer as a method for enabling/disabling compilation of particular sections of code?

This may be a matter of style, but there's a bit of a divide in our dev team and I wondered if anyone else had any ideas on the matter...

Basically, we have some debug print statements which we turn off during normal development. Personally I prefer to do the following:

//---- SomeSourceFile.cpp ----

#define DEBUG_ENABLED (0)

...

SomeFunction()
{
int someVariable = 5;

#if(DEBUG_ENABLED)
printf("Debugging: someVariable == %d", someVariable);
#endif
}

Some of the team prefer the following though:

// #define DEBUG_ENABLED

...

SomeFunction()
{
int someVariable = 5;

#ifdef DEBUG_ENABLED
printf("Debugging: someVariable == %d", someVariable);
#endif
}

...which of those methods sounds better to you and why? My feeling is that the first is safer because there is always something defined and there's no danger it could destroy other defines elsewhere.

I myself prefer:

#if defined(DEBUG_ENABLED)

Since it makes it easier to create code that looks for the opposite condition much easier to spot:

#if !defined(DEBUG_ENABLED)

vs.

#ifndef(DEBUG_ENABLED)

The first seems clearer to me. It seems more natural make it a flag as compared to defined/not defined.

I've always used #ifdef and compiler flags to define it...

I think it's entirely a question of style. Neither really has an obvious advantage over the other.

Consistency is more important than either particular choice, so I'd recommend that you get together with your team and pick one style, and stick to it.

Both are exactly equivalent. In idiomatic use, #ifdef is used just to check for definedness (and what I'd use in your example), whereas #if is used in more complex expressions, such as #if defined(A) && !defined(B).