Enum.GetValues(typeof(....)) not returning the proper enum values

Question

Given this code:

public enum Enum1
{
    ONE,
    TWO
}

public enum Enum2
{
    A,
    B
}

This code returns ONE, TWO:

foreach (Enum1 e in Enum.GetValues(typeof(Enum1)))
{
  Console.WriteLine(e);
}

But this code, instead of failing (because Enum2 e is used with typeof(Enum1)), returns A, B:

foreach (Enum2 e in Enum.GetValues(typeof(Enum1)))
{
    Console.WriteLine(e);
}

Why is that?

Answer 1

Because under the covers Enums are just ints - the second returns the values of Enum1, but really those values are just 0 and 1. When you cast those values to the type Enum2 these are still valid and correspond to the values "A" and "B".

Answer 2

Because the values of your enums are implicitly integers:

public enum Enum1
{
    ONE = 0,
    TWO = 1
}

public enum Enum2
{
    A = 0,
    B = 1
}

The values of Enum1 are being implicitly converted to integers and then to values of Enum2. If you redefined Enum1 as follows...

public enum Enum1
{
    ONE = 0,
    TWO = 1,
    THREE = 2,
}

...then it would fail not return "A, B", because there is no value in Enum2 for the integer value 2