C# array within a struct

Question

Want to do this: (EDIT: bad sample code, ignore and skip below)

struct RECORD {     char[] name = new char[16];     int dt1; } struct BLOCK {     char[] version = new char[4];     int  field1;     int  field2;     RECORD[] records = new RECORD[15];     char[] filler1 = new char[24]; } 

But being unable to declare array sizes in struct, how do I reconfigure this?

EDIT: The reason for the layout is I'm using BinaryReader to read a file written with C structs. Using BinaryReader, and a C# struct union (FieldOffset(0)), I'm wanting to load the header as a byte array, then read it as it was intended originally.

[StructLayout(LayoutKind.Sequential)] unsafe struct headerLayout {     [FieldOffset(0)]     char[] version = new char[4];     int fileOsn;     int fileDsn;     // and other fields, some with arrays of simple types }  [StructLayout(LayoutKind.Explicit)] struct headerUnion                  // 2048 bytes in header {     [FieldOffset(0)]     public byte[] headerBytes;      // for BinaryReader     [FieldOffset(0)]     public headerLayout header;     // for field recognition } 

Answer 1

Use fixed size buffers:

[StructLayout(LayoutKind.Explicit)] unsafe struct headerUnion                  // 2048 bytes in header {     [FieldOffset(0)]     public fixed byte headerBytes[2048];           [FieldOffset(0)]     public headerLayout header;  } 

Alternativ you can just use the struct and read it with the following extension method:

private static T ReadStruct<T>(this BinaryReader reader)         where T : struct {     Byte[] buffer = new Byte[Marshal.SizeOf(typeof(T))];     reader.Read(buffer, 0, buffer.Length);     GCHandle handle = default(GCHandle);     try     {         handle = GCHandle.Alloc(buffer, GCHandleType.Pinned);         return (T)Marshal.PtrToStructure(handle.AddrOfPinnedObject(), typeof(T));     }     finally     {         if (handle.IsAllocated)              handle.Free();     } } 

Answer 2

Unmanaged structures can contain embedded arrays. By default, these embedded array fields are marshaled as a SAFEARRAY. In the following example, s1 is an embedded array that is allocated directly within the structure itself.

Unmanaged representation struct MyStruct {     short s1[128]; } 

Arrays can be marshaled as UnmanagedType.ByValArray, which requires you to set the MarshalAsAttribute.SizeConst field. The size can be set only as a constant. The following code shows the corresponding managed definition of MyStruct. C#VB

[StructLayout(LayoutKind.Sequential)] public struct MyStruct {    [MarshalAs(UnmanagedType.ByValArray, SizeConst=128)] public short[] s1; }