public class Employee 

{

    private int _type;

    private double _monthlySalary;

    private double _commission;

    private double _bonus;

    public const int ENGINEER = 0;

    public const int SALESMAN = 1;

    public const int MANAGER = 2;

    public Employee(int type) 

    {

        _type = type;

    }

    public double GetAmount() 

    {

        switch (_type) 

        {

            case ENGINEER:

                return _monthlySalary;

            case SALESMAN:

                return _monthlySalary + _commission;

            case MANAGER:

                return _monthlySalary + _bonus;

            default:

                throw new ArgumentException("_type");

        }

    }

​

}