On Fri, Jan 19, 2007 at 03:23:24PM -0500, Peter Jay Salzman wrote:
[snip]
> > #define CHECK_FOR_NULLITITY(var) \
> > if ( (var) == NULL ) \
> > { \
> > puts( #var " is null." ); \
> > exit(EXIT_FAILURE); \
> > }
[snip]
> Yeah, in the real code I did. I was actually using cerr (it's C++ code).
There's another oddity with macros when using with C++ streams:
#define PRINT_ME(a) do { std::cout << a << std::endl; } while(0)
int main() {
int i = 1;
PRINT_ME(i+5);
}
This will generate error, because PRINT_ME(i+5) expands to:
std::cout << i+5 << std::end;
and since + has higher precedence than <<, syntax error gets generated
at compile time. Once again, the "enclose everything in define" rule of
thumb kicks in:
#define PRINT_ME(a) do { std::cout << (a) << std::endl; } while(0)
which allows the expansion of the macro to be:
std::cout << (i+5) << std::end;
and all is well...
-Mark
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