Chaining Bool values give opposite result to expected

Question

Unthinkingly I wrote some code to check that all the values of a struct were set to 0. To accomplish this I used:

bool IsValid() {
    return !(0 == year ==          


        

Answer 1

== groups from left to right, so if all values are zero then:

0 == year // true
(0 == year) == month // false, since month is 0 and (0 == year) converts to 1
((0 == year) == month) == day // true

And so on.

In general, x == y == z is not equivalent to x == y && x == z as you seem to expect.