Re: G_ARRAY_LENGTH for glib.h?

[Sebastian Wilhelmi <wilhelmi ira uka de>]

Hi Tim,

> this is probably compiler version dependant, i did these kinds of tests
> about 2 yers ago (and iirc tested the same code with lcc as well), also
> have you tried compiling this code with -g?
> remeber, gcc is not the only compiler out there ;)

Yes, and it only works, when compiled with -O1 (or more). But I think, it
would be ok to add a test at least for gcc with optimize. Something like the
following, thus preventing everybody with a gcc from doing such stupid
mistakes:

/* Count the number of elements in an array. The array must be defined
 * as such; using this with a dynamically allocated array will give
 * incorrect results.
 */
#if defined(__GNUC__) && defined(__OPTIMIZE__)
/* The following function is only declared, but never defined. If we
 * use the gnu compiler with optimization turned on, this function is
 * not referenced, when using G_N_ELEMENTS with arrays only. Otherwise
 * the linking will fail. */
int G_N_ELEMENTS_error_the_provided_object_is_not_an_array();
#  define G_N_ELEMENTS(arr)						\
  ((((gpointer)&(arr))!=((gpointer)&((arr)[0])))?			\
    (G_N_ELEMENTS_error_the_provided_object_is_not_an_array()):		\
    (sizeof(arr) / sizeof((arr)[0])))
#else
#  define G_N_ELEMENTS(arr)		(sizeof(arr) / sizeof((arr)[0]))
#endif


Bye,
Sebastian
-- 
Sebastian Wilhelmi                   |            här ovanför alla molnen
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