In C, does (x==y==z) behave as I'd expect?

Question

Can I compare three variables like the following, instead of doing if((x==y)&&(y==z)&&(z=x)) ? [The if statement should execute if all three variables have the same value. These are booleans.]

if(debounceATnow == debounceATlast == debounceATlastlast)
{
 debounceANew = debounceATnow;
}
else
{
 debounceANew = debounceAOld;
}

Answer 1

No, it does not.

x == y is converted to int, yields 0 or 1 , and the result is compared to z . So x==y==z will yield true if and only if (x is equal to y and z is 1) or (x is not equal to y and z is 0)

What you want to do is

if(x == y && x == z)

Answer 2

否。等式检查从左侧关联，逻辑结果与数字进行比较，因此表达式2 == 2 == 1解析为(2 == 2) == 1 ，这反过来给出1 == 1结果为1 ，这可能不是你想要的。

Answer 3

You can actually type something like this:

int main()
{
        const int first = 27,
                  second = first,
                  third = second,
                  fourth = third;
        if (!((first & second & third) ^ fourth))
            return 1;
        return 0;
}