C# variable scope for instantiating a class

Question

I am going through the FizzBuzz kata and trying to do it in as much of an object orientated way as possible, just started learning C#. In that pursuit, I am trying to use a class called, MessageStore to store various strings and integers to be passed and referenced during runtime without having to hard code as much as possible.

The problem I am having is that I don't think I understand properly how or where to instantiate my class so that is can be called further into the program.

I have tried instantiating at the top of the Program class with MessageStore returnString and assigning that instance to variable within Main, returnString = new MessageStore();.

I am trying to call the returnString instance in the first part of the `FizzOrBuzz method, but I can't, not sure of this is down to scope?

The error that is showing, is Cannot access non-static field, 'returnString' in static context I have tried removing static from the Main constructor but that still leaves with with issues.

Any help much appreciated.

 using System;
using System.CodeDom;
using System.Collections.Generic;
using System.Linq;
using System.Security.Cryptography.X509Certificates;
using System.Text;
using System.Threading.Tasks;

namespace FizzBuzz
{
    class Program
    {
        // Instantiating MessageStore
        MessageStore returnString;

        static void Main(string[] args)
        {
           // Assigning instance a variable name
           returnString = new MessageStore();

            PlayFizzBuzz(100);
            MessageHelper(MessageStore.ReturnCompletedMessage());
            Console.ReadLine();
        }

        public static void PlayFizzBuzz(int startNumber)
        {
            for (int i = startNumber; i >= 0; i--)
            {
                if (i == 0)
                {
                    break;
                }
                MessageHelper(FizzOrBuzz(i));
            }
        }

        public static String FizzOrBuzz(int numberInLoop)
        {
            if (MultipleCheck(numberInLoop, MessageStore.ReturnThree()) && MultipleCheck(numberInLoop, MessageStore.ReturnFive()))
            {
                // Trying to call instance with variable name
                return returnString.ReturnFizzBuzz();
            }
            if (MultipleCheck(numberInLoop, MessageStore.ReturnThree()))
            {
                return MessageStore.ReturnFizz();
            }
            if (MultipleCheck(numberInLoop, MessageStore.ReturnFive()))
            {
               return MessageStore.ReturnBuzz();
            }
            else
                return numberInLoop.ToString();
        }

        public static bool MultipleCheck(int numberToAssess, int multiple)
        {
            return (numberToAssess % multiple == 0) ? true : false;
        }


       public static void MessageHelper(string messageText)
       {
           Console.WriteLine(messageText);
       }

        class MessageStore
        {
            public static string ReturnFizz() { return "Fizz!"; }
            public static string ReturnBuzz() { return "Buzz!"; }
            public static string ReturnFizzBuzz() { return "FizzBuzz!"; }
            public static string ReturnCompletedMessage() { return "Looks like we're done here!"; }
            public static int ReturnThree() { return 3; }
            public static int ReturnFive() { return 5; }
        }

    }
}

If your underlying purpose is to learn more about object orientation then FizzBuzz isn't a great problem to pick, since you'll just end up adding complexity without seeing much benefit from the OO part. Instead you want some sort of problem involving a hierarchy of related objects (shapes and animals being the canonical examples). — Matthew Strawbridge, Jul 10 '16 at 21:13

score 1 · Answer 1 · answered Jul 10 '16 at 20:49

1

Make this line static

static MessageStore returnString;

This is because all your functions are static, hence they can only access static class members, so the most easy solution is to mark the object as static, since you will have only one instance of it at a time.

answered Jul 10 '16 at 20:49

MoustafaS

1,991
11
20

1

Make `FizzOrBuzz` method `static` as well, to avoid another same error! – Nikhil Vartak Jul 10 '16 at 20:51
@NikhilVartak Yeah I must have have changed that when I was messing about earlier, thanks! – 3therk1ll Jul 10 '16 at 20:52
I stil have the issue when trying to call `returnString.ReturnFizzBuzz()`. `Cannot be accessed with an instance reference`? – 3therk1ll Jul 10 '16 at 20:53
@RichC Because you made all the class itesm in the MessageStore to be static, why did you do this ? Either remove static from all of them, or use it Directly like MessageStore.ReturnFizzBuzz() – MoustafaS Jul 10 '16 at 20:55
@MoustafaS NO great reason, brand new to `C#` is all. That has fixed it though. Thanks – 3therk1ll Jul 10 '16 at 20:56
Don't forget to mark as an answer then ;) @RichC – MoustafaS Jul 10 '16 at 20:57

C# variable scope for instantiating a class

1 Answers1