Calling variables from different classes c#

Question

I'm trying to write a program that have two classes, and call 2 variables from one to another but i got two errors that saying " 'Area.Circle' does not contain a definition for 'result1' " and " 'Area.Circle' does not contain a definition for 'result2' ". how can i solve this problem?

using System;

namespace Area
{
    class Circle
    {
        public static void Area()
        {
            Console.WriteLine("Enter the radius of the first circle:   ");
            int r1 = Convert.ToInt32(Console.ReadLine());
            Console.WriteLine("Enter the radius of the second circle:   ");
            int r2 = Convert.ToInt32(Console.ReadLine());
            double pi = Math.PI;
            double result1 = pi * r1 * r1;
            double result2 = pi * r2 * r2;
            Console.WriteLine("The area of the first circle is {0}\nThe area of the second circle is {1}\n", result1, result2);
        }
    }

    class Minimum
    {
        static void Main(string[] args)
        {
            Circle.Area();
            Circle one = new Circle();

            double min = Math.Min(Circle.result1, Circle.result2);
            Console.WriteLine("min");

        }
    }
}

You defined result1 and result2 inside a method. That means those variables are local to that method and cannot be called outside it. If you want to keep those variables around you need to declare them at the class level (inside Circle but outside Area). — eddie_cat
– eddie_cat, Commented Oct 30, 2014 at 14:50

Rob Hardy · Accepted Answer · 2014-10-30 15:04:09Z

4

The problem is that you are defining result1 and result2 within the scope of the Area() method. Declare them at the class level, public and static, and they will be accessible.

As the method Area() is static the variables will have to also be static in order to be accessed from within it. You are accessing the variables as static from your other class though, so that should work.

edited Oct 30, 2014 at 15:04

answered Oct 30, 2014 at 14:50

Rob Hardy

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3 Comments

Servy Over a year ago

Then they won't be accessible in the Area method.

Rob Hardy Over a year ago

They will if they also are static or if the Area method is not static, and since he's calling Circle.result1 and Circle.result2, they should be

Servy Over a year ago

1) You didn't mention that 2) That would still be terrible design.

Yuval Itzchakov · Accepted Answer · 2014-10-30 14:55:58Z

2

That's because result1 and result2 are local variables inside your Area method. You have to make them public and at the class level (consider turning them into Properties perhaps):

class Circle
{
    public double Result1 { get; set; }
    public double Result2 { get; set; }
}

One thing to note is that if you keep Area declared as a static method, you wont be able to use instance members inside the calling function.

edited Oct 30, 2014 at 14:55

answered Oct 30, 2014 at 14:50

Yuval Itzchakov

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Comments

Servy · Accepted Answer · 2014-10-30 14:59:43Z

0

When you have a method that computes values it needs to return the values that it computes to the caller. Storing them in a local variable isn't exposing them to the caller of the method. In this case, since you have two values to return, you'll need to encapsulate those two values in another class that can be returned instead. You could make a custom class, or simply use a general purpose class such as Tuple.

public static Tuple<double, double> Area()
{
    Console.WriteLine("Enter the radius of the first circle:   ");
    int r1 = Convert.ToInt32(Console.ReadLine());
    Console.WriteLine("Enter the radius of the second circle:   ");
    int r2 = Convert.ToInt32(Console.ReadLine());
    double pi = Math.PI;
    double result1 = pi * r1 * r1;
    double result2 = pi * r2 * r2;
    Console.WriteLine("The area of the first circle is {0}\nThe area of the second circle is {1}\n", result1, result2);
    return Tuple.Create(result1, result2);
}

When you call Area you can then store the result of the method in a variable and access that data later on.

answered Oct 30, 2014 at 14:59

Servy

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1 Comment

Sinatr Over a year ago

Static methods mostly used to immediately return result, so this answer is most applicable in my opinion. OP uses new Circle(), perhaps he needs to read more about static usage. If Area() would be non static, then using new, calling method and getting results as properties looks better.

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