I'm writing a function that takes an Enum
and casts it to uint
. From what I've seen when casting to int
, you have to cast it to an object first: (int) (object) myEnumValue
. If you write (int) myEnumValue
you get a compile time exception.
Now, when I tried to cast it to uint, I was expecting that (uint) (object) myEnumValue
would be alright. It compiles nicely, but when run, it generates an InvalidCastException
. So to get it to work, I've used
(uint) (int) (object) myEnumValue
I think it looks funny, so I'm quite happy, but why is it so?
Maybe it would have been more correct to ask why it is not possible to cast object
to uint
, but I'm interested in whether there is another way to go from an Enum
to uint
. Is there?
Edit:
The context is a function, something like this:
public static uint ToUInt (Enum e)
{
return (uint) (int) (object) e;
}
Edit 2:
The best solution was as mentioned by thecoop:
Convert.ToUInt32(e)
The (uint) (object) myEnum
approach fails because, by default, C# enums use int
as their underlying type, and an int
is what they get turned into when they're boxed. The C# syntax makes it look like enums inherit from their underlying type (like enum MyEnum : uint
).
You have to explicitly tell the compiler to unbox from object
to int
first, then do a numerical conversion from int
to uint
. (Even though the syntax is the same, unboxing from object
to a value type is a different process from casting between int
and uint
.)
From what I've seen when casting to int, you have to cast it to an object first:
(int) (object) myEnum
. If you write(int) myEnum
you get a compile time exception.
Not true. You can directly cast an enum value to an integer type.
Now, when I tried to cast it to uint, I was expecting that (uint) (object) myEnum would be alright. It compiles nicely, but when run, it generates an InvalidCastException. So to get it to work, I've used:
(uint) (int) (object) myEnum
I think it looks funny, so I'm quite happy, but why is it so?
When you cast an enum value to object
, it'll be boxed as its underlying type, which is int
by default. You cannot unbox a boxed value to any type other than its actual type directly. Even this will fail:
short s = 10;
object o = s;
int i = (int)o; // throws `InvalidCastException` while `int i = (int)s;` works.
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