3 ms·

Addition on bools is XOR.

• CamperBob2 9y ago
  Not by C++'s convention. It may be compiler-dependent, but all of the compilers I have within easy reach treat addition of bools as an 'or' operation. bool a = true; bool b = true; bool c = a + b; This leaves c set to true. Basically it gets promoted to int, turned into a value of 2, and demoted back to bool. Either way it's highly nonstandard not to implement a bitwise-or operation on a boolean type. It's a violation of the "principle of least surprise" as well as a portability hazard. No upside that I can imagine.
  • asveikau 9y ago
    I have been writing C for a while and never saw anyone add bools with +. Why do this when there is completely unambiguous || ? I get suspicious of being fast and loose with conversions between int and bool. This is implicitly required when working with operators like &&, ||, ==, etc., and working with pre-C99 bools and library typedefs. But assigning anything other than 1 or 0 is asking for problems. There is a whole class of bugs that shows up in security bugs involving assigning someone's machine-word-sized Boolean expression into someone else's byte sized bool, losing bits, and flipping from true to false. I sometimes feel there is a ^^ operator that should be there and is missing, in the same way that we have && and || corresponding to & and |. I have occasionally faked it with a macro: #define XOR(A,B) (((A) ? 1 : 0) ^ ((B) ? 1 : 0)) The ? here eliminates the problems from using larger != 1 quantities as true, as above.