On Tue, Apr 19, 2005 at 03:28:07PM +0200, Etienne Lorrain wrote: > Hi, > > Just a minor thing, but I hit this problem times to times, I know > the CPP preprocessor has no warning like "end of line ignored"... > GCC-3.3.5 and 3.4.3.
This is just order of operations. > [EMAIL PROTECTED]:~/projet$ cat > tmp.c > #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 > #warning OPTION2 unset > #else > #warning OPTION2 set > #endif That's #if (1 | 4) & (2 == 0). 2 != 0, so 5&0 == 0. -- Daniel Jacobowitz CodeSourcery, LLC
