Reusing Legacy DLLs in C#

using System;
using System.Runtime.InteropServices;

namespace ConsoleApplication1
{
	/// <summary>
	/// Summary description for Class1.
	/// </summary>
	class MyDLL {
		[DllImport("legacy",EntryPoint = "MyAppend",ExactSpelling = true,CharSet = CharSet.Ansi,CallingConvention = CallingConvention.Cdecl)]
		public static extern unsafe IntPtr Append(
			IntPtr ptr,
			[MarshalAs(UnmanagedType.LPStr)]
			string arg1,
			[MarshalAs(UnmanagedType.LPStr)]
			string arg2,
			[MarshalAs(UnmanagedType.LPStr)]
			string arg3, bool isLast);

		[DllImport("legacy",EntryPoint = "KillBuffer",ExactSpelling = true,CharSet = CharSet.Ansi,CallingConvention = CallingConvention.Cdecl)]
		public static extern unsafe void StringDispose(IntPtr ptr);

	}
	class Class1
	{
		/// <summary>
		/// The main entry point for the application.
		/// </summary>
		[STAThread]
		static void Main(string[] args)
		{
			//
			// TODO: Add code to start application here
			//
			IntPtr target = IntPtr.Zero;
			target = MyDLL.Append(target,"xx","yy","zzz",false);
			target = MyDLL.Append(target,"xx","yy","zzz",false);
			target = MyDLL.Append(target,"xx","yy","zzz",true);
			Console.WriteLine("Returned: {0}",Marshal.PtrToStringAnsi(target));
			MyDLL.StringDispose(target);
		}
	}
}