C＃中的struct union问题 [英] Problem of struct union in C#

问题描述

我有这个结构：

I Have this struct:

public struct A
{
    public int first;
}
public struct B
{
    [MarshalAs(UnmanagedType.ByValArray, SizeConst=32)]
    public char[] first;
}
[StructLayout(LayoutKind.Explicit)]
public struct CUnion
{
    [FieldOffset(0)]
    public A _a;

    [FieldOffset(0)]
    public B _b;
}
public struct C
{
    public int type;
    public CUnion u;
}

但是当我实例化新的C struct时，这个错误

but when i instance new C struct, this error

C c = new C();

// Exception
// An unhandled exception of type 'System.TypeLoadException' occurred in Microsoft.VisualStudio.HostingProcess.Utilities.dll
// Additional information: Could not load type 'CUnion' from assembly '...' because it contains an object field at offset 0 that is incorrectly aligned or overlapped by a non-object field.

任何ideia？



PS：固定内存不适用，因为内存不是senquencial

推荐答案

请试试这个

Please Try this

public struct A
   {
       public int first;
   }
   [StructLayout(LayoutKind.Sequential, Pack = 1)]
   public struct B
   {
       [MarshalAs(UnmanagedType.ByValArray, SizeConst = 32)]
       public char[] first;
   }
   [StructLayout(LayoutKind.Explicit)]
   public struct CUnion
   {
       [FieldOffset(4)]
       public A _a;

       [FieldOffset(0)]
       public B _b;
   }
   public struct C
   {
       public int type;
       public CUnion u;
   }

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