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What is the correct way of casting (in C++/CLI) from a native code enum to a managed code enum which contain the same enum values? Is there any difference with using the C# way of casting like for example (int) in C++/CLI.

Lopper
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2 Answers2

43

Assuming your native code is

enum shape_type_e
{
    stUNHANDLED     = 0,            //!< Unhandled shape data.
    stPOINT         = 1             //!< Point data.
    ...
};

and your managed code is

public enum class ShapeType
{
    Unhandled   = 0,
    Point       = 1,
    ...
};

You can cast from the native to the managed using

shape_type_e nativeST = stPOINT;
ShapeType managedST = static_cast<ShapeType>(nativeST);
Debug.Assert(managedST == ShapeType::Point);

I always use static_cast, not the C# way of casting.

Community
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mcdave
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    From the above code, I suppose you are casting from native to managed enum. What about the other way round from managed to native? – Lopper Dec 10 '09 at 06:53
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    Static cast is your friend both ways ... nativeST = static_cast(managedST); – mcdave Dec 10 '09 at 07:01
  • Based on your comment to @Lopper, could you then change the text in your answer to clarify that the example is demonstrating native-to-managed (and not the other way around as it currently states). – Glenn Slayden Jan 21 '17 at 23:05
1

It depends. for example, if you have a CLI enum that has an underlying type of ushort, it cannot hold a vallue of 257. By default the CLI enum is based on int, which should be fine in most cases. If your native C++ code use unsigned 32bit ints/64bit ints as the underlying type if enums, switch the base of your CLI enum to UInt32, long or ulong.

Sheng Jiang 蒋晟
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    I won't have this issue because both enum are of type int. But which type of cast should be used in this case? Should it be const_cast, static_cast, dynamic_cast, reinterpret_cast, safe_cast or just the C# cast (an example is (int))? – Lopper Dec 10 '09 at 01:40