On Wed, Jul 22, 2009 at 10:42, John (Eljay) Love-Jensen<eljay@xxxxxxxxx> wrote:
> Hi Paulo,
>
> Since the early days of K&R C and Unix, the define NDEBUG has been used, and is still used by the C <assert.h> header file, and by the C++ <cassert> header file.
>
> To get the debug behavior, you need to compile like this:
>
> gcc Foo.c
>
> To get the release (non-debug) behavior, you need to compile like this:
>
> gcc -DNDEBUG Foo.c
>
> To isolate debug-only code blocks, you do this:
>
> #ifndef NDEBUG
> DebugTrace("yada yada");
> #endif
>
> To isolate release-only code blocks, you do this:
>
> #ifdef NDEBUG
> ReleaseOnly("yada yada");
> #endif
>
> To create a (say) TRACE macro that is only in your code for debug-only, you could do this:
>
> #include <iostream>
> #ifdef NDEBUG
> #define TRACE(x) ((void)0)
> #else
> #define TRACE(x) std::cerr << x << std::endl
> #endif
>
> The use of _DEBUG is something I've only run across in Microsoft's headers. (It may be used by others as a convention, but I haven't bumped into that yet.)
>
> You are at liberty to use your own preprocessor symbol to indicate debug-vs-nondebug compilations. DEBUG, _DEBUG, __DEBUG__, __DEBUG or whatever. Be warned, though, that _DEBUG, __DEBUG, __DEBUG__ are all reserved symbols. So you are better off using DEBUG or PFS_DEBUG (for examples).
>
> I find NDEBUG a little confusing because of the double-negative #ifndef NDEBUG, but that's just me. I'm a bear of small brain.
>
> HTH,
> --Eljay
>
Thanks Eljay for the quick answer. Your answer help me a lot,
specially about the TRACE trick.
About the "reserved symbols", I tried to discover it and didn't found
anywhere. Is there any command or gcc parameter to know the reserved
symbols? The only way that I got is to create a program to print all
known defines.
Thanks again,
Paulo Flabiano Smorigo
