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:-