CODEWITHSUNDEEP
c#typesunion
Krupa Shah Bhavsar
Krupa Shah Bhavsar

Reputation: 1

Option for Union datatype in C#

I have implemented one program in C++ which has union Datatype. Now I want to convert that program into c#.

I want to used same structure in c# but don't know what can be used in place of union datatype.

We are using Visual Studio 2013 and framework 4.5.2.0

Upvotes: 0

Views: 620

Answers (2)

TheGeneral
TheGeneral

Reputation: 81493

There is no out-of-the-box Union data type in C#

However, you can fake-it with a struct and the FieldOffset attribute I guess. You can do this because of the need for interoperability, also you sometimes see it used for a fast non-cast type conversion. Be warned though, it's considered extremely hacky.

[StructLayout(LayoutKind.Explicit)]
struct SomeType
{
   [FieldOffset(0)] public int Myint;
   [FieldOffset(0)] public byte Byte1;
   [FieldOffset(1)] public byte Byte2;
   [FieldOffset(2)] public byte Byte3;
   [FieldOffset(3)] public byte Byte4;

}

Usage

var someType = new SomeType();

Console.WriteLine(someType.Myint);

someType.Byte1 = 2;
Console.WriteLine(someType.Myint);

someType.Byte2 = 4;
Console.WriteLine(someType.Myint);

Output

0
2
1026

Note : I would seriously consider using the more common language features in C#, rethink the problem and not use this hack.

Upvotes: 1

SkiSharp
SkiSharp

Reputation: 171

Unfortunately, C# provides no direct out of the "box solution" in comparison to C++' Union data type. However, BitConverter is an option if you're using the union to map the bytes of one of the types of the other.

For example:

int x = 15;
float y = BitConverter.ToInt32(BitConverter.GetBytes(x), 0);

& vice versa:

float y = 15f;
int x = BitConverter.ToInt32(BitConverter.GetBytes(y), 0);

Upvotes: 0

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