C# Execute assembly sequence and other os function

1,execute Assembly sequence

using System;
using System.Reflection;

class Program
{
    public delegate uint Ret1ArgDelegate(uint arg1);
    static uint PlaceHolder1(uint arg1) { return 0; }

    public static byte[] asmBytes = new byte[]
    {        
0x89,0xD0, // MOV EAX,EDX
0xD1,0xC8, // ROR EAX,1
0xC3       // RET
    };

    unsafe static void Main(string[] args)
    {
    fixed(byte* startAddress = &asmBytes[0]) // Take the address of our x86 code
    {
        // Get the FieldInfo for "_methodPtr"
        Type delType = typeof(Delegate);
        FieldInfo _methodPtr = delType.GetField("_methodPtr", BindingFlags.NonPublic | BindingFlags.Instance);

        // Set our delegate to our x86 code
        Ret1ArgDelegate del = new Ret1ArgDelegate(PlaceHolder1);
        _methodPtr.SetValue(del, (IntPtr)startAddress);

        // Enjoy
        uint n = (uint)0xFFFFFFFC;
        n = del(n);
        Console.WriteLine("{0:x}", n);
    }
    }
}

　　

using System;
using System.Collections.Generic;
using System.Runtime.InteropServices;

namespace DynamicX86
{
    class Program
    {
        const uint PAGE_EXECUTE_READWRITE = 0x40;
        const uint MEM_COMMIT = 0x1000;

        [DllImport("kernel32.dll", SetLastError = true)]
        static extern IntPtr VirtualAlloc(IntPtr lpAddress, uint dwSize, uint flAllocationType, uint flProtect);

        private delegate int IntReturner();

        static void Main(string[] args)
        {
            List<byte> bodyBuilder = new List<byte>();
            bodyBuilder.Add(0xb8);
            bodyBuilder.AddRange(BitConverter.GetBytes(42));
            bodyBuilder.Add(0xc3);
            byte[] body = bodyBuilder.ToArray();
            IntPtr buf = VirtualAlloc(IntPtr.Zero, (uint)body.Length, MEM_COMMIT, PAGE_EXECUTE_READWRITE);
            Marshal.Copy(body, 0, buf, body.Length);

            IntReturner ptr = (IntReturner)Marshal.GetDelegateForFunctionPointer(buf, typeof(IntReturner));
            Console.WriteLine(ptr());
        }
    }
}