Program.cs

using System;
using System.Collections.Generic;

namespace CompositePattern
{
  interface IEmployee
  {
    float GetSalary();
    string GetRole();
    string GetName();
  }


  class Developer : IEmployee
  {
    private string mName;
    private float mSalary;

    public Developer(string name, float salary)
    {
      this.mName = name;
      this.mSalary = salary;
    }

    public float GetSalary()
    {
      return this.mSalary;
    }

    public string GetRole()
    {
      return "Developer";
    }

    public string GetName()
    {
      return this.mName;
    }
  }

  class Designer : IEmployee
  {
    private string mName;
    private float mSalary;

    public Designer(string name, float salary)
    {
      this.mName = name;
      this.mSalary = salary;
    }

    public float GetSalary()
    {
      return this.mSalary;
    }

    public string GetRole()
    {
      return "Designer";
    }

    public string GetName()
    {
      return this.mName;
    }
  }
  class Organization
  {
    protected List<IEmployee> employees;

    public Organization()
    {
      employees = new List<IEmployee>();
    }

    public void AddEmployee(IEmployee employee)
    {
      employees.Add(employee);
    }

    public float GetNetSalaries()
    {
      float netSalary = 0;

      foreach (var e in employees) {
        netSalary += e.GetSalary();
      }
      return netSalary;
    }
  }
  class Program
  {
    static void Main(string[] args)
    {
      var developer = new Developer("John", 5000);
      var designer = new Designer("Arya", 5000);

      var organization = new Organization();
      organization.AddEmployee(developer);
      organization.AddEmployee(designer);
      Console.WriteLine("Net Salary of Emmployees in Organization is {0:c}", organization.GetNetSalaries());
      Console.ReadLine();
    }
  }
}