macro directive question

For the following directive snippet, would the contents of the if directive executive only when DBG is equal to a non-zero value?

Code:

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#if DBG
#define SHOULD(b)      { if (!(b)) DEBUGMESSAGE( ("FAILURE CONDITION ENCOUNTERED") ); }
#else
#define SHOULD(b)      /* empty value */
#endif

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You could always try it and find out, but yes, that's how it works.

what you are looking for is assert() in <cassert>.

Quote:

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Originally Posted by cyberfish

what you are looking for is assert() in <cassert>.

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Although assert() only works in Debug mode (i.e. if NDEBUG isn't defined); so if that's what you want, go with assert(), otherwise creating your own is fine.
assert() also ends the program, which might not always be what you want.

By defining a macro to nothing, the entire macro will be reduces to nothing after the preprocessor processes it, so nothing is left afterwards.
So you could say that it will only execute in debug.