Equality operator overloads: Is (x!=y) == (!(x==y))?

Question

Does the C++ standard guarantee that (x!=y) always has the same truth value as !(x==y)?

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I know there are many subtleties inv

Answer 1

No. You can write operator overloads for == and != that do whatever you wish. It probably would be a bad idea to do so, but the definition of C++ does not constrain those operators to be each other's logical opposites.