structlayout

Consider the following code: using System; using System.Runtime.InteropServices; namespace Demo { class Program { static void Main(string[] args) { const string test = "ABCDEF"; // Strings are immutable, right? char[] chars = new StringToChar{str=test}.chr; chars[0] = 'X'; // On an x32 release or debug build or on an x64 debug build, // the following prints "XBCDEF". // On an x64 release build, it prints "ABXDEF". // In both cases, we have changed the contents of 'test' without using // any 'unsafe' code... Console.WriteLine(test); } } [StructLayout(LayoutKind.Explicit)] public struct

I'm trying to understand why the second example below works with no issues, but the first example gives me the exception below. It seems to me that both examples should give an exception based on the description. Can anyone enlighten me? Unhandled Exception: System.TypeLoadException: Could not load type 'StructTest.OuterType' from assembly 'StructTest, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null' because it contains an object field at offset 0 that is incorrectly aligned or overlapped by a non-object field. at StructTest.Program.Main(String[] args) Press any key to continue . . .

Why does LayoutKind.Sequential work differently if a struct contains a DateTime field? Consider the following code (a console app which must be compiled with "unsafe" enabled): using System; using System.Runtime.InteropServices; namespace ConsoleApplication3 { static class Program { static void Main() { Inner test = new Inner(); unsafe { Console.WriteLine("Address of struct = " + ((int)&test).ToString("X")); Console.WriteLine("Address of First = " + ((int)&test.First).ToString("X")); Console.WriteLine("Address of NotFirst = " + ((int)&test.NotFirst).ToString("X")); } } } [StructLayout