C# Interface

This sample code is my favorite way to demonstrate how interface work, I can see students in "20483 Programming in C#" are all understand why we have to implement interface and what is the meaning of contract to the implemented classes. 

 

 

using System; namespace ConsoleApplication1 {    interface IDataAccess    {            void SelectTop10();    }    class OracleDataAccess : IDataAccess    {       public void SelectTop10(){         Console.WriteLine("SELECT * FROM TABLE1 WHERE ROWNUM <= 10;");       }    }    class SQLDataAccess : IDataAccess    {       public void SelectTop10(){         Console.WriteLine("SELECT TOP 10 * FROM TABLE1;");       }    }    class Program    {       static void Main(string[] args)       {          OracleDataAccess oracle = new OracleDataAccess();          oracle.SelectTop10();          IDataAccess sql = new SQLDataAccess();          sql.SelectTop10();       }    } }

 

Here is the output:-

 

C# Delegate with return value

I have written another simple Delegate code to share with students in "20483 Programming in C#", this code showing the delegate with parameters and return value and how we supply the parameters and receive the return value.

 

 

using System; namespace EventDelegatePOC {    delegate int MyDelegate(string s);    class Program    {       static int SayHello(string HelloMessage)       {           Console.WriteLine("Hello {0}", HelloMessage);           return 100;       }       static int SayGoodBye(string GoodbyeMessage)       {           Console.WriteLine("Good Bye {0}", GoodbyeMessage);           return -999;       }       static void Main(string[] args)       {           MyDelegate x = new MyDelegate(SayHello);           MyDelegate y = new MyDelegate(SayGoodBye);           int a = x("President");           int b = y("Sayonara");           Console.WriteLine("a = {0}", a);           Console.WriteLine("b = {0}", b);       }    } }

Here is the ouput:-

C# Event Delegate Tutorial

 

Here is the simple tutorial for understanding C# Event and Delegate, I believe the code explain by itself:

 

using System; namespace EventDelegate2 {    delegate void MyDelegate();    class Program    {       static event MyDelegate myEvent;       static void Main(string[] args)       {           myEvent += new MyDelegate(Sing);           myEvent += new MyDelegate(Dance);           myEvent.Invoke();       }               static void Sing()       {           Console.WriteLine("Sing");       }       static void Dance()       {           Console.WriteLine("Dance");       }     } }

 

Here is the output: