using System;

using System.Runtime.InteropServices;

​

 //The Struct needs to be annotated as "Explicit Layout", like this:

 [System.Runtime.InteropServices.StructLayout(LayoutKind.Explicit)]

 struct IpAddress

 {

   //The "FieldOffset:" means that this Integer starts 

   //a offset 0, in bytes, (with sizeof(int) = 4 bytes length): 

   [System.Runtime.InteropServices.FieldOffset(0)]

   public int intAddress;

​

   //Offset 0, (length sizeof(byte) = 1 byte)...   

   [System.Runtime.InteropServices.FieldOffset(0)]

   public byte Byte1;

​

   //Offset 1, (length sizeof(byte) = 1 byte)...     

   [System.Runtime.InteropServices.FieldOffset(1)]

   public byte Byte2;

​

   //Offset 2, (length sizeof(byte) = 1 byte)...   

   [System.Runtime.InteropServices.FieldOffset(2)]

   public byte Byte3;

   //Offset 3, (length sizeof(byte) = 1 byte)...    

   [System.Runtime.InteropServices.FieldOffset(3)]

   public byte Byte4;     

   public IpAddress(int address) {

         //All elements have to be initialized. it is a good idea to initialize the 

         //ones not being explicitly set first.

         Byte1 = Byte2 = Byte3 = Byte4 = 0;

​

         //Now, when we init the Int, the Bytes will change too.

         //If we had done this backwards, it would zero out the intAddress. 

         intAddress = address;

   }

     //Now we can use the explicit layout to access the 

     //bytes separately, without doing any conversion

     public override string ToString() {

         return (new System.Text.StringBuilder()).Append(Byte1).Append('.')

                 .Append(Byte2).Append('.')

                 .Append(Byte3).Append('.')

                 .Append(Byte4).Append('.').ToString();

     }

 }

​

​

public class MainClass { 

​

    public static void Main()

    {

     var ip = new IpAddress((new Random()).Next());

     Console.Out.WriteLine(ip + "\t= " + ip.intAddress);

     ip.Byte1 = 100;

     Console.Out.WriteLine(ip + "\t= " + ip.intAddress);

    }   

}