What guarantees does C provide about enum ordinal values

Question

When I convert enum to integer type, what can I expect?

• Does the first variant have value of 0?

• Does the variant ordinal number increment by 1?

Assume that I did not explicitly provide the values.

---

If you like code, then the questions are here:

enum foo
{
    A,
    B,
};

int
main(void)
{
    assert(A == 0);
    assert(B == 1);
}

Answer 1

Does the first variant have value of 0?

Yes.

Does the variant ordinal number increment by 1?

Yes.

What guarantees does C provide about enum ordinal values

From https://port70.net/~nsz/c/c11/n1570.html#6.7.2.2 :

[...] If the first enumerator has no =, the value of its enumeration constant is 0. Each subsequent enumerator with no = defines its enumeration constant as the value of the constant expression obtained by adding 1 to the value of the previous enumeration constant. [...]