using System;

public class Program

{

    public static void Main()

    {

        Calculator myCalc = new Calculator();

        Console.WriteLine ("Add:" + myCalc.Add(1,2) + " " + myCalc.Add(1,2).GetType());

        Console.WriteLine ("Subtract:" + myCalc.Subtract(1,2)+ " " + myCalc.Subtract(1,2).GetType());

        Console.WriteLine ("Multiply:" + myCalc.Multiply(1,2)+ " " + myCalc.Multiply(1,2).GetType());

        Console.WriteLine ("Divide:" + myCalc.Divide(1,2)+ " " + myCalc.Divide(1,2).GetType());

        Console.WriteLine ("////////////////////////string//////////////////////////////////");

        StringCalculator myStrCalc = new StringCalculator();

        Console.WriteLine ("Add:" + myStrCalc.Add(1,2) + " " + myStrCalc.Add(1,2).GetType());

        Console.WriteLine ("Subtract:" + myStrCalc.Subtract(1,2)+ " " + myStrCalc.Subtract(1,2).GetType());

        Console.WriteLine ("Multiply:" + myStrCalc.Multiply(1,2)+ " " + myStrCalc.Multiply(1,2).GetType());

        Console.WriteLine ("Divide:" + myStrCalc.Divide(1,2)+ " " + myStrCalc.Divide(1,2).GetType());

        Console.WriteLine ("////////////////////////Tedans//////////////////////////////////");

        TedansCalc tedansCalc = new TedansCalc();

        Console.WriteLine ("Add:" + tedansCalc.Add(typeof(double),1,2) + " " +  tedansCalc.Add(typeof(double),1,2).GetType());

        Console.WriteLine ("Subtract:" + tedansCalc.Subtract(typeof(string),1,2) + " " +  tedansCalc.Subtract(typeof(string),1,2).GetType());

        Console.WriteLine ("Multiply:" + tedansCalc.Multiply(typeof(string),1,2) + " " +  tedansCalc.Multiply(typeof(string),1,2).GetType());

        Console.WriteLine ("Divide:" + tedansCalc.Divide(typeof(string),1,2) + " " +  tedansCalc.Divide(typeof(string),1,2).GetType());

​

        Console.WriteLine ("////////////////////////Johns//////////////////////////////////");

        JohnsCalc johnscalc = new JohnsCalc();

        string s = null;

        double d = 0;

        johnscalc.Add(ref s, ref d,1,2);

        Console.WriteLine (s + " " + d);

    }

    public static double Add(double x, double y)

    {

        return x + y;

    }

}

​

​

​

​

public class Calculator

{

    public double Add(double x, double y)

    {

        return x + y;

    }

    public double Subtract(double x, double y)

    {

        return x - y;

    }

    public double Divide(double x, double y)

    {

        return x / y;

    }

    public double Multiply(double x, double y)

    {

        return x * y;

    }

}

​

//inherits calculator

public class StringCalculator

{

Calculator myCalc = new Calculator();

    public string Add(double x, double y)

    {

        return myCalc.Add(x,y).ToString();

    }

    public string Subtract(double x, double y)

    {

        return myCalc.Subtract(x,y).ToString();

    }

    public string Divide(double x, double y)

    {

        return myCalc.Divide(x,y).ToString();

    }

    public string Multiply(double x, double y)

    {

        return myCalc.Multiply(x,y).ToString();

    }

}

​

​

​

​

​

​

​

​

public class TedansCalc

{

    public object Add(System.Type type, double x, double y)

    {

        double val = x + y;

        if (type == typeof(string))

            {return val.ToString();}

        else if (type == typeof(double))

            {return val;}

        else return "error";

    }

    public object Subtract(Type type, double x, double y)

    {

        double val =  x - y;

        if (type == typeof(string))

            {return val.ToString();}

        else if (type == typeof(double))

            {return val;}

        else return "error";

    }

    public object Divide(Type type, double x, double y)

    {

        double val =  x / y;

        if (type == typeof(string))

            {return val.ToString();}

        else if (type == typeof(double))

            {return val;}

        else return "error";

    }

    public object Multiply(Type type, double x, double y)

    {

        double val =  x * y;

        if (type == typeof(string))

            {return val.ToString();}

        else if (type == typeof(double))

            {return val;}

        else return "error";

    }

}

​

public class JohnsCalc

{

    public void Add(ref String s, ref Double d, Double x, Double y)

    {

        double val = x + y;

        s = val.ToString();

        d = val;

    }

​

}

​

​

​

​