Csharp/CSharp Tutorial/Class/Extension

Adding extension method for int

<source lang="csharp">using System; using System.Text; using System.Reflection; using System.Runtime.rupilerServices; public static class MyExtensions {

   public static void DisplayDefiningAssembly(this object obj)
   {
       Console.WriteLine(obj.GetType().Name);
       Console.WriteLine(Assembly.GetAssembly(obj.GetType()));
   }
   public static int ReverseDigits(this int i)
   {
       char[] digits = i.ToString().ToCharArray();
       Array.Reverse(digits);
       string newDigits = new string(digits);
       return int.Parse(newDigits);
   }

} class Program {

   static void Main(string[] args)
   {
       int myInt = 987;
       myInt.DisplayDefiningAssembly();
       Console.WriteLine("{0} is reversed to {1}", myInt, myInt.ReverseDigits());
       Console.ReadLine();
   }

}</source>

Adding extension to Stream

<source lang="csharp">using System.ruponentModel; using System.IO; using System.Net;

   public static class StreamUtilWithExtensions
   {
       const int BufferSize = 8192;
       public static void CopyTo(this Stream input,Stream output)
       {
           byte[] buffer = new byte[BufferSize];
           int read;
           while ((read = input.Read(buffer, 0, buffer.Length)) > 0)
           {
               output.Write(buffer, 0, read);
           }
       }
       public static byte[] ReadFully(this Stream input)
       {
           using (MemoryStream tempStream = new MemoryStream())
           {
               CopyTo(input, tempStream);
               if (tempStream.Length == tempStream.GetBuffer().Length)
               {
                   return tempStream.GetBuffer();
               }
               return tempStream.ToArray();
           }
       }
   }

   class MainClass
   {
       static void Main()
       {
           WebRequest request = WebRequest.Create("http://nfex.ru");
           using (WebResponse response = request.GetResponse())
           using (Stream responseStream = response.GetResponseStream())
           using (FileStream output = File.Create("data.dat"))
           {
               responseStream.CopyTo(output);
           }
       }
   }</source>

Adding reverse operation to string

<source lang="csharp">using System; using System.Collections.Generic; using System.Linq; using System.Text;

   public static class ExtensionLibExtensions
   {
       public static string ReverseString(this string inputString)
       {
           return new string(inputString.ToCharArray().Reverse().ToArray());
       }
   }
   class Program
   {
       static void Main(string[] args)
       {
           string sourceString = "this is a test";
           Console.WriteLine("String backwards: {0}", sourceString.ReverseString());
       }
   }</source>

Add title case to string class

<source lang="csharp">using System; using System.Collections.Generic; using System.Linq; using System.Text;

   public static class ExtensionLibExtensions
   {
       public static string ToTitleCase(this string inputString, bool forceLower)
       {
           inputString = inputString.Trim();
           if (inputString == "")
           {
               return "";
           }
           if (forceLower)
           {
               inputString = inputString.ToLower();
           }
           string[] inputStringAsArray = inputString.Split(" ");
           StringBuilder sb = new StringBuilder();
           for (int i = 0; i < inputStringAsArray.Length; i++)
           {
               if (inputStringAsArray[i].Length > 0)
               {
                   sb.AppendFormat("{0}{1} ",
                      inputStringAsArray[i].Substring(0, 1).ToUpper(),
                      inputStringAsArray[i].Substring(1));
               }
           }
           return sb.ToString(0, sb.Length - 1);
       }
   }
   class Program
   {
       static void Main(string[] args)
       {
           string sourceString = "this is a test";
           Console.WriteLine("String with title casing: {0}", sourceString.ToTitleCase(true));
       }
   }</source>

conflicting extension methods

<source lang="csharp">using System;

   public static class ExtensionMethods
   {
       public static string Substring(this string s, int startIndex, int endIndex)
       {
           if (startIndex >= 0 && startIndex <= endIndex && endIndex < s.Length)
               return s.Substring(startIndex, endIndex - startIndex);
           else
               return s;
       }
   }
   public class Tester{
       public static void Main()
       {
           string hello = "Hello";
           Console.WriteLine("hello.Substring(2, 3) = {0}", hello.Substring(2, 3));
       }
   }</source>

extension method

<source lang="csharp">using System;

   public static class ExtensionMethods
   {
       public static string Right(this string s, int n)
       {
           if (n < 0 || n > s.Length)
               return s;
           else
               return s.Substring(s.Length - n);
       }
   }
   public class Tester
   {
       public static void Main()
       {
           string hello = "Hello";
           Console.WriteLine("hello.Right(-1) = {0}", hello.Right(-1));
           Console.WriteLine("hello.Right(0) = {0}", hello.Right(0));
       }
   }</source>

Extension Method On Null Reference

<source lang="csharp">using System; using System.ruponentModel;

   static class NullUtil
   {
       public static bool IsNull(this object x)
       {
           return x == null;
       }
   }
   class MainClass
   {
       static void Main()
       {
           object y = null;
           Console.WriteLine(y.IsNull());
           y = new object();
           Console.WriteLine(y.IsNull());
       }
   }</source>