Re: preceding (void) as a do-nothing
On Dec 10, 4:47 am, mtall....@gmail.com wrote:
Hello,
Is the code below valid C++ ? While it compiles under gcc 4.3, I'm
not sure whether "(void)(arg1, arg2)" is a portable way to get the
functionality of "do nothing and ignore all arguments".
#if defined(DO_DEBUG)
#define debug_print do_print
#else
#define debug_print (void)
#endif
inline void do_print(int a, int b)
{
std::cout << a << b << std::endl;
}
int main(int argc, char** argv)
{
debug_print(1,2);
return 0;
}
Ah, very keen... But it doesn't really ignores the 'arguments'. :)
When compiled w/o DO_DEBUG you have a coma-separated expression `
(1,2)' cast to type `void':
(void)(1,2);
If expression happen to have any side-effects they are still executed,
because 'arguments' are calcuated first and then the result is
ignored:
debug_print(printf("abc\n"), printf("def\n"));
abc
def
However, this ought to be suitable for debugging/logging purposes
because you don't want the side effects (other than actual logging) in
the 'debug mode'. :)
--
Cheers,
Alex
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