C# Cannot convert type 'String' to 'AreaCal.VolumeSphere'

Question

I am new to C# and trying to make a volume cal that allows you to choose the shape you want to find the volume of I am trying to do that with read line. I am getting Cannot convert type 'String' to 'AreaCal.VolumeSphere' at the read line in static void main

using System;

namespace AreaCal
{

    class VolumeSphere
    {
        double pi = 3.14159265359;
        double ft = 1.333333333333333333333333333333333333;
        double r;
        public void Details()
        {
            Console.WriteLine("Volume of a Circle");
            Console.WriteLine ("Type Radius");
            r = Convert.ToInt32 (Console.ReadLine ());

        }
        public double GetVolume()
        {
            return ft * pi * r * r * r;
        }
        public void Display()
        {
            Console.WriteLine ("Volume: {0}", GetVolume());
        }

    }
    class MainClass
    {
        public static void Main (string[] args)
        {
            VolumeSphere Sphere = new VolumeSphere ();
            Sphere = (Console.ReadLine ());
            if (Sphere != null)
                Console.WriteLine ("awwww");

        }
    }
}

Answer 1

In reading your question you mention that you are trying to select multiple calculators, in your example you are trying to assign your keyboard input to your VolumeSphere Object. Here is a quick and dirty implementation of a menu for your calculator, you can play with it and expand it to meet your needs.

class MainClass
{
    static void Main(string[] args)
    {
        int value;
        bool run;

        run = true;
        while(run)
        {
            Console.WriteLine("Calculator Menu");
            Console.WriteLine("1: Compute Volume of a Sphere");
            Console.WriteLine("2: Compute Something else");
            Console.WriteLine("etc,etc,etc");

            if (int.TryParse(Console.ReadLine(), out value))
            {
                switch (value)
                {
                    case 1:
                        VolumeSphere Sphere = new VolumeSphere();
                        Sphere.Details();
                        Console.WriteLine(Sphere.GetVolume());
                        Sphere.Display();
                        break;
                    case 2:
                        break;
                    case 3:
                        break;

                    default:
                        Console.WriteLine("GoodBye");
                        run = false;
                        break;

                }

            }
        }
        Console.WriteLine("Press Any Key to Exit");
        Console.ReadLine();
    }
}

Answer 2

Sphere is an object of class VolumeSphere but you are assigning a string Console.ReadLine here that is wrong. Probably you wanted to do something like:

VolumeSphere Sphere = new VolumeSphere();
Sphere.Details();
Sphere.Display();

But your requirement is not clear. So please provide more details on it. And also consider using constructor to pass radius value to your VolumeSphere class.

Answer 3

VolumeSphere Sphere = new VolumeSphere();
Sphere = (Console.ReadLine ());

This is throwing the error. Console.Readline() returns a string read in from standard input. You are trying to assign this to the variable Sphere, which you declared to be of type VolumeSphere. I am not sure what you are reading from standard input, but I assume it is radius.

You need to do this instead;

string radius = Console.ReadLine();
VolumeSphere Sphere = new VolumeSphere(Convert.ToDouble(radius));

This passes the string parameter converted to a double to the VolumeSphere constructor, which you are going to define like this inside of class VolumeSphere:

public VolumeSphere(double r)
{
   this.r = r;
}

You should also remove the Details method and put its writelines in the main before you read your input because it is better to encapsulate your models and user interface.