Hi John,
I aggree with our MVP, and here is a simple example:
If you still have problem on this issue, please let me know.
Thanks for using MSDN Newsgroup!
<code unmanaged part>
typedef struct _mytype
{
    int *data;
}mytype;
extern "C" __declspec(dllexport)
mytype* init(int size)
{
 mytype *p_mytype = new mytype();
 p_mytype->data = new int[size];
 for(int i = 0; i < size;i++)
 {
     p_mytype->data[i] = i;
 }
 return p_mytype;
}
</code unmanaged part>
<code>
using System;
using System.Runtime.InteropServices;

namespace Interop_CS
{
    /// <summary>
    /// Summary description for Class1.
    /// </summary>
    class Class1
    {
        /// <summary>
        /// The main entry point for the application.
        /// </summary>
        [STAThread]
        static void Main(string[] args)
        {   
            int size = 10;
            IntPtr p = init(size);
            MyType t = Marshal.PtrToStructure(p,typeof(MyType)) as MyType;
            int[] s = new int[size];
            Marshal.Copy(t.data,s,0,size);

            //read from the data
            for(int i = 0; i < size; i++)
            {
                Console.WriteLine(s[i]);
            }
            //change the s
            //write it back to t.data
            Marshal.Copy(s,0,t.data,size);

            //you should provide an corresponding function do free the memory.
            //free_mytype();
        }
        /*
            typedef struct _mytype
            {
                int *data;
            }mytype;
        */
        [StructLayout(LayoutKind.Sequential)]
        public class MyType
        {
            //because you allocated memory in your unmanaged code, we can't marshal
it to array.
            //or the address will lost, and the memory will not be freed.
            public IntPtr data;
        }
        [DllImport("Interop_DLL_Stub.dll")]
        public extern static IntPtr init(int size);
    }
}
</code>

Best regards,

Ying-Shen Yu [MSFT]
Microsoft Online Partner Support
Get Secure! - www.microsoft.com/security

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