Inner Classes In C#
By Saju

Like Java, in C# also inner classes are possible. The program code demonstrates the implementation of inner classes and structures in classes. If we want to create an instance out side the class the inner class and inner structure should be public. Unlike java there will only one EXE is created, but in java more than one class files will create. The following program is self explanatory with proper output

//Here Demonstrating class ,innerclass and inner structure
//Demonstrating method overriding with abstract class

using System;
abstract class admin
 {
   abstract public void  getdetails(string x,string y);
   abstract public void showdetails();
 }

//Declaring Main class

class student
 {
   public string std_code;
   public string std_name;
   public student()
    {
     // fcode="A090"; won't work because it is an inner class field
      std_code=" ";
      std_name=" ";
    }
   public void getdata(string str1,string str2)
    {
      std_code=str1;
      std_name=str2;
    }
   public void show()
    {
      Console.WriteLine("Student Code {0} ",std_code);
      Console.WriteLine("Student Name {0} ",std_name);
    }

    //Declaring inner structure Examination for storing examination details

    public struct Examination 
      {
        public string ExamCode;
        public string ExamName;
        public void setDetails(string str1,string str2)
         {
           ExamCode=str1;
           ExamName=str2;
         }
        public string[] getdetails()
         {
           string []temp;
           temp=new string[2];
           temp[0]=ExamCode;
           temp[1]=ExamName;
           return temp;
         }

      }//End of inner structure Examination

    //Declaring Inner class faculty

    public class faculty : admin
        {
          public string fcode;
          public string fname;
          public faculty()
           {
            //std_code="";Won't work,Only Static member can be permitted
            fcode=" ";
            fname=" ";
           }
          public override void getdetails(string str1,string str2)
           {
             fcode=str1;
             fname=str2;
           }
          public override void showdetails()
           {
             Console.WriteLine("\nFaculty Code {0} ",fcode);
             Console.WriteLine("Faculty Name {0} ",fname);
           }
      } //End Of class faculty

}
//**********************************
class classTest
 {
   static void Main()
    {
       //Instantiating an object of type student

       student xx=new student();

       //Instantiating an object of type inner faculty

       student.faculty yy=new student.faculty();

       //Putting values into the public field of object type student

       xx.getdata("S0089","Ajit");

       //Displaying the contents of object of type student

       xx.show();

       //Evoking the function getdetails() of inner class faculty
       //for putting values into the public fields

       yy.getdetails("V0089","Vishnu Namboodiri");

       //Displaying the components of innerclass faculty

       yy.showdetails();

       //creating the instance of inner structure Examination of
       //class student

       student.Examination ee=new student.Examination();

       // putting values into inner structure Examination
       // of class student

       ee.setDetails("St9080","GVKM Tvm");

       //Displaying the contents of inner structure Examination
       //using foreach looping structure

       foreach(string t in ee.getdetails())
        {
          Console.Write("{0} ",t);
        }

       //Overriding the student.faculty with abstract class admin

       Console.WriteLine("\nOutput After Late Binding");

       admin adm=new student.faculty();
       adm.getdetails("P009","Pradeep Iyangar");
       adm.showdetails();
    }
}
//*******************************************************************


// Output of the above program

/*
   Student Code S0089 
   Student Name Ajit 

   Faculty Code V0089 
   Faculty Name Vishnu Namboodiri 
   St9080 GVKM Tvm 
   Output After Late Binding

   Faculty Code P009 
   Faculty Name Pradeep Iyangar 
    
                      */