Unsafeクラスのサンプル的な奴

Code.cs

using System;
using System.Runtime.CompilerServices;

namespace UnsafeSample
{
    public class Code
    {
        public void Add()
        {
            Console.WriteLine($"{nameof(Add)} Start");
            var ar = new int[] { 0, 1, 2, 3, 4, 5 };
            int i3 = Unsafe.Add(ref ar[0], 3);
            Console.WriteLine($"0..5's offset 3 is {i3}"); // 3
            Console.WriteLine($"{nameof(Add)} End");
        }

        public void AreSame()
        {
            Console.WriteLine($"{nameof(AreSame)} Start");
            var a = new Object();
            var b = new Object();
            ref object ra1 = ref a;
            ref object ra2 = ref a;
            ref object rb = ref b;
            Console.WriteLine($"{nameof(ra1)} and {nameof(ra2)} areSame: {Unsafe.AreSame(ref ra1, ref ra2)}"); // true
            Console.WriteLine($"{nameof(ra1)} and {nameof(rb)} areSame: {Unsafe.AreSame(ref ra1, ref rb)}"); // false
            Console.WriteLine($"{nameof(AreSame)} End");
        }

        public void As()
        {
            Console.WriteLine($"{nameof(As)} Start");
            object a = "object";
            ref object ra = ref a;
            string ca = Unsafe.As<string>(a);
            string cra = Unsafe.As<object, string>(ref ra);
            Console.WriteLine($"{nameof(ca)}: {ca}, {nameof(cra)}: {cra}"); // object, object
            Console.WriteLine($"{nameof(As)} End");
        }

        public unsafe void AsPointer()
        {
            Console.WriteLine($"{nameof(AsPointer)} Start");
            var ar = new int[] { 0, 1, 2, 3, 4, 5 };
            void* pointer = Unsafe.AsPointer(ref ar[0]);
            int* intptr = (int*)pointer;
            Console.WriteLine($"*({nameof(intptr)}+1) = {*(intptr + 1)}"); // 1
            Console.WriteLine($"{nameof(AsPointer)} End");
        }

        public unsafe void AsRef()
        {
            Console.WriteLine($"{nameof(AsRef)} Start");
            var ar = new int[] { 0, 1, 2, 3, 4, 5 };
            fixed (int* intptr = &ar[0])
            {
                void* pointer = (void*)(intptr + 4);
                int i4 = Unsafe.AsRef<int>(pointer);
                Console.WriteLine($"{nameof(intptr)} + 4 = {i4}"); // 4
            }
            Console.WriteLine($"{nameof(AsRef)} End");
        }

        public void CopyBlock()
        {
            Console.WriteLine($"{nameof(CopyBlock)} Start");
            var ar1 = new byte[] { 0, 1, 2, 3, 4, 5 };
            var ar2 = new byte[ar1.Length];
            Unsafe.CopyBlock(ref ar2[0], ref ar1[0], (uint)ar1.Length);
            Console.WriteLine("Copied");
            foreach (byte b in ar2)
            {
                Console.WriteLine(b); // 0, 1, 2, 3, 4, 5
            }
            Console.WriteLine($"{nameof(CopyBlock)} End");
        }

        public void InitBlock()
        {
            Console.WriteLine($"{nameof(InitBlock)} Start");
            var ar = new byte[6];
            Unsafe.InitBlock(ref ar[0], 3, (uint)ar.Length);
            Console.WriteLine("Init");
            foreach (byte b in ar)
            {
                Console.WriteLine(b); // 3, 3, 3, 3, 3, 3
            }
            Console.WriteLine($"{nameof(InitBlock)} End");
        }

        public unsafe void Read()
        {
            Console.WriteLine($"{nameof(Read)} Start");
            int a = 10;
            int* intptr = &a;
            void* pointer = (void*)intptr;
            Console.WriteLine($"Read intptr: {Unsafe.Read<int>(pointer)}"); // 10
            Console.WriteLine($"{nameof(Read)} End");
        }

        public void SizeOf()
        {
            Console.WriteLine($"{nameof(SizeOf)} Start");
            Console.WriteLine($"string size: {Unsafe.SizeOf<string>()}"); // 8 (in 64bit OS)
            Console.WriteLine($"{nameof(SizeOf)} End");
        }
    }
}

Program.cs

using System;
using UnsafeSample;

namespace ConsoleApp
{
    class Program
    {
        static void Main(string[] args)
        {
            var code = new Code();
            code.Add();
            Console.WriteLine();
            code.AreSame();
            Console.WriteLine();
            code.As();
            Console.WriteLine();
            code.AsPointer();
            Console.WriteLine();
            code.AsRef();
            Console.WriteLine();
            code.CopyBlock();
            Console.WriteLine();
            code.InitBlock();
            Console.WriteLine();
            code.Read();
            Console.WriteLine();
            code.SizeOf();
        }
    }
}