Struct def TypeLoadException

[Erakis]

Hi,

What wrong with my struct declaration ?
When I run my program, I got a TypeLoadException.

[StructLayout(LayoutKind.Explicit, CharSet=CharSet.Ansi, Size=16)] 
struct InfoRegister 
{ 
   [FieldOffset(0)] 
   public uint TargetIdBitField; 

   [FieldOffset(4)] 
   [MarshalAs(UnmanagedType.ByValArray, SizeConst = 9) ] 
   public byte[] Label; 

   [FieldOffset(13)] 
   public byte Mode; 

   [FieldOffset(14)] 
   public byte Index; 

   [FieldOffset(15)] 
   public byte CS; 

   [FieldOffset(0)] 
   [MarshalAs(UnmanagedType.ByValArray, SizeConst = 16) ] 
   public ushort[] StructInUShortArray; 
}

Thanks

 

[chiph]

My first guess would be that you aren't allocating any space for your arrays.

My second guess is that your ushort array is overlaying offset 0. C# does not have unions.

Chip H.


____________________________________________________________________
If you want to get the best response to a question, please read FAQ222-2244 first

 

[Erakis]

Hi,

I cannot pre-allocate space for my array because C-Sharp doesn't allow default constructor (empty) on struct object.

I already test other types of union using C-Sharp and it work well.

Here it is an exemple :

public struct SpecialFloat
{
   [FieldOffset(0)] public float FloatValue;

   [FieldOffset(0)] public ushort UShortValue1;
   [FieldOffset(2)] public ushort UShortValue2;

   [FieldOffset(0)] public byte ByteValue0;
   [FieldOffset(1)] public byte ByteValue1;
   [FieldOffset(2)] public byte ByteValue2;
   [FieldOffset(3)] public byte ByteValue3;
}

This pattern works perfectly...
So how can I make InfoRegister struct to works ?

Thanks

 

[chiph]

You might have to do something ugly like this:

   [FieldOffset(4)]
   public byte Label1;
   [FieldOffset(5)]
   public byte Label2;
   [FieldOffset(6)]
   public byte Label3;
    :
    :
   [FieldOffset(12)]
   public byte Label9;

Chip H.


____________________________________________________________________
If you want to get the best response to a question, please read FAQ222-2244 first

 

[Erakis]

Hi,

Ouch ! Ungly as you said, not really usefull

 

[IonelBurtan]

There are three problems with your struct (or better name it union):

1. StructInUShortArray is a "object" on 4 bytes which points to an array of ushorts so it cannot overlap a value type. If you put two of this kind in a same union you will see that it works, but if you put one value type with one array it won't.

2. You miss an (ArraySubType = UnmanagedType.U2) name parameter in the MarshallAs attribute for StructInUShortArray.

3. The SizeConst member does not reflect the syze in bytes (see the MSDN help), but:
"Indicates the number of elements in the fixed-length array or the number of characters (not bytes) in a string to import"

Now, take the above into account, and rewrite your struct and I am sure you will get it right.

Side Note: I admit, the error message from the TypeLoadException is kind of dumb and missleading, but "There are spots even in the sun", isn't it.

HTH,



s-)

Blessed is he who in the name of justice and goodwill, sheperds the weak through the valley of darkness...

http://www20.brinkster.com/ionelb

 

[Erakis]

Hi,

Thanks for you help, it is really appreciated
Here is my struct again :

[StructLayout(LayoutKind.Explicit, CharSet=CharSet.Ansi, Size=16)] 
struct InfoRegister 
{ 
   [FieldOffset(0)] 
   public uint TargetIdBitField; 

   [FieldOffset(4)] 
   [MarshalAs(UnmanagedType.ByValArray, ArraySubType = UnmanagedType.I1, SizeConst = 9) ] 
   public byte[] Label; 

   [FieldOffset(13)] 
   public byte Mode; 

   [FieldOffset(14)] 
   public byte Index; 

   [FieldOffset(15)] 
   public byte CS; 

   [FieldOffset(0)] 
   [MarshalAs(UnmanagedType.ByValArray, ArraySubType = UnmanagedType.U2, SizeConst = 8) ] 
   public ushort[] StructInUShortArray; 
}

I did change for point 2 and 3 but for you tips #1 I understand the problem but I don't know how to solve it.

I cannot do that, this is not what I need.

   [FieldOffset(4)]
   public byte Label1;
   [FieldOffset(5)]
   public byte Label2;
   [FieldOffset(6)]
   public byte Label3;
    :
    :
   [FieldOffset(12)]
   public byte Label9;

This struct need to be filled by a DLL (unmanaged) function that required a ushort[] pointer.

Thanks