[英]Union in c# with StructLayout
I have multiple structs that all starts with a header struct. 我有多个结构,都以头结构开头。 Like this
像这样
public struct BaseProtocol {
public Header header;
public Footer footer;
};
The header is 标题是
public struct Header {
public Byte start;
public Byte group;
public Byte dest;
public Byte source;
public Byte code;
public Byte status;
};
The problem now is that I need to union them with a Byte[]. 现在的问题是我需要将它们与Byte []结合起来。 I tried it with this
我试过这个
[StructLayout( LayoutKind.Explicit, Size=255 )]
public struct RecBuffer {
[FieldOffset( 0 )]
public Header header;
[FieldOffset( 0 )]
[MarshalAs( UnmanagedType.ByValArray, ArraySubType = UnmanagedType.I1, SizeConst = 255 )]
public Byte[] buffer;
};
When I fill the buffer with data I can't get the data from the header. 当我用缓冲区填充数据时,我无法从标题中获取数据。 How can I make c# do the same as I can do with union in c++?
如何使c#与c ++中的union相同?
Byte[] is a reference type field, which you cannot overlay with a value type field. 字节[]是引用类型字段,您不能使用值类型字段覆盖它。 You need a fixed size buffer and you need to compile it with
/unsafe
. 您需要一个固定大小的缓冲区,您需要使用
/unsafe
编译它。 Like this: 像这样:
[StructLayout(LayoutKind.Explicit, Size = 255)]
public unsafe struct RecBuffer
{
[FieldOffset(0)]
public long header;
[FieldOffset(0)]
[MarshalAs(UnmanagedType.ByValArray, ArraySubType = UnmanagedType.I1, SizeConst = 255)]
public fixed Byte buffer[255];
};
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