c中的定义：
typedef struct _test
{
    int* a;
    int size1;
    int size2;
}test;
c#中定义：
    public class test
        {            
            [MarshalAs(UnmanagedType.ByValArray/*, SizeConst = IMAGE_SIZE*/)]
            public int[] a;
            [MarshalAs(UnmanagedType.I4)]
            public int size1;
            [MarshalAs(UnmanagedType.I4)]
            public int size2;
        }


    private static void ss()
        {
           test t = new test();
           t.a = new int[IMAGE_SIZE];
            for (int i = 0; i < IMAGE_SIZE; i++)
                t.a[i] =i;
            t.size1 = 3;
            t.size2 = 5;
            testfun(t);
            //IntPtr ptr = Marshal.AllocHGlobal(Marshal.SizeOf(t));
            //Marshal.StructureToPtr(t, ptr, true);
            //testfun(ptr);
            
            //test tt =(test)Marshal.PtrToStructure(ptr, typeof(test));
         
            //MessageBox.Show(tt.a[0].ToString());
            //MessageBox.Show(tt.b);
            //Marshal.FreeHGlobal(ptr);
        }

不知那里出了问题，传值一直有问题，数组可以传递，但是两个整形则传不过去，是一个很大的整数。请问问题出在那里？

[DllImport("FaceLib.dll", EntryPoint = "testfun", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        public static extern int testfun(test s);

出现的错误是：
尝试读取或写入受保护的内存。这通常指示其他内存已损坏。