On Tue, Apr 19, 2005 at 03:28:07PM +0200, Etienne Lorrain wrote: > > #define OPTION1 0x0001 > > #define OPTION2 0x0002 > > #define OPTION3 0x0004 > > #define OPTION4 0x0008 > > #define CONFIGURATION (OPTION1 | OPTION3) > > // There is the problem: the "== 0" is ignored > > #if CONFIGURATION & OPTION2 == 0
On Tue, Apr 19, 2005 at 09:33:44AM -0400, Daniel Jacobowitz wrote: > That's #if (1 | 4) & (2 == 0). 2 != 0, so 5&0 == 0. Yes, the fact that the bitwise binary operators have a lower precedence than the relational operators is probably the biggest botch in C and its derivative languages; I've been C-ing for 20 years, and I still make these kinds of errors from time to time. GCC has the "suggest parentheses" warning elsewhere (to catch people writing "if (foo = 0)" and the like; maybe there should be a warning for this one as well.
