How to change variable from one class using another in C#

Question

The title may sound a bit confuse, but what I want to do is basicaly create a class, declare a public int with the default value of 0, then inside the Program class I permanently change the value of this variable in a function, and if I print this value using another function, it will print the value set in the first function. For example:

using System;
{

    class Global
    {
       public int variable = 0;
    }

    class Program
    {
        static void Main(string[] args)
        {
            Global test = new Global();
            test.variable = 10;
            //it makes no sense in this code to use another function, 
            //but in my other project it does
            Function();
            Console.ReadLine();
        }
        
        static void Function()
        {
            Global test = new Global();
            //should print 10
            Console.WriteLine(test.variable);
        }
        
    }
    
}

Just change the method to `void Function(Global instance)` and call it using `test.variable = 10; Function(test);` and remove `Global test = new Global();` from this method. — , Aug 08 '21 at 20:15
With you current sample make variable static `public static int variable = 0;` — Fabio, Aug 08 '21 at 20:16
You are creating a ***new*** global instance using `new`, which means it starts at zed again. **Where** you declare a variable determines its scope! Suggested reading: **[Scope of Variables in C#](https://www.geeksforgeeks.org/scope-of-variables-in-c-sharp/)** also **[new operator (C# reference)](https://learn.microsoft.com/en-us/dotnet/csharp/language-reference/operators/new-operator)** — Ňɏssa Pøngjǣrdenlarp, Aug 08 '21 at 20:17
Also rename Global coz not suitable to *WhatIsTheGoalOfMyClass*: [Naming Convention in c#](https://stackoverflow.com/questions/1618316/naming-convention-in-c-sharp) • [C# Naming Conventions](https://www.c-sharpcorner.com/UploadFile/8a67c0/C-Sharp-coding-standards-and-naming-conventions/) • [C# Coding Standards and Naming Conventions](https://github.com/ktaranov/naming-convention/blob/master/C%23%20Coding%20Standards%20and%20Naming%20Conventions.md) • [C# Coding Conventions (C# Programming Guide)](https://docs.microsoft.com/dotnet/csharp/programming-guide/inside-a-program/coding-conventions) — , Aug 08 '21 at 20:20
Indeed; you've caused this confusion for yourself by calling the class Global when it really isn't global at all — Caius Jard, Aug 08 '21 at 20:23
The context of what's in your other project will probably give a better idea of what you are trying to achieve. Could you post that? The example you've given here doesn't make sense, and I suspect you might be asking the wrong question. With better context, you'll get better answers. — Bryan, Aug 11 '21 at 14:24

score 1 · Accepted Answer · answered Aug 08 '21 at 20:25

You could create a static class if you don't want to bother with injection like this:

public static class Global
{
    public int variable = 0;
}
class Program
{
    static void Main(string[] args)
    {
        Global.variable = 10;
    }
    static void Function()
    {
        Console.WriteLine(Global.variable);
    }
}

or you could just inject the class through as a parameter from wherever you call it.

public class Global
{
    public int variable = 0;
}
class Program
{
    static void Main(string[] args)
    {
        var test = new Global();
        test.variable = 10;
    }
    static void Function(Global global)
    {
        Console.WriteLine(global.variable);
    }
}

If you want to permanently change this variable inside every class you could use a static class, but then you wouldn't be able to create instances of it (if you wanted other variables to be non-static.

I would recommend looking into IServiceProviders because they can be really useful if the Function() method is inside another class and you want to pass through the Global class.

Sorry for the question that might seem too obvious to you, but it's because I'm new to programming. Now how do I call the "Function" function in static void Main in the second case? — dino_monkey, Aug 08 '21 at 21:00
As long as they are both static you should just be able to put Function(); If you added a parameter just add that in the parenthesis. — jallmen, Aug 09 '21 at 21:08

How to change variable from one class using another in C#

1 Answers1