CODEWITHSUNDEEP
c#
Sofia
Sofia

Reputation: 93

Passed to class variable not being updated

This should sound like a really basic question, but I haven't been able to find an answer (even tho I know for sure there are plenty), I guess my Googling skills are bad, or maybe I don't know what to search for.

I have this code:

using System;

public class Program
{   
    public static void Main()
    {
        var service = new Service();

        service.Execute();
    }
}

public class Service
{
    private int _foo;

    public void Execute()
    {
        _foo = 1;

        var bar = new Bar(_foo);

        _foo = 2;

        bar.WriteLine();
    }
}

public class Bar
{
    private readonly int _foo;

    public Bar(int foo)
    {
        _foo = foo;
    }

    public void WriteLine()
    {
        Console.WriteLine(_foo);
    }
}

How can I make it so it prints 2? (basically the new value after Bar has been initialized)

I tried using ref but no luck.

Upvotes: 1

Views: 155

Answers (1)

TheGeneral
TheGeneral

Reputation: 81473

What you are trying to do doesn't make sense for a value type

Value types and reference types are the two main categories of C# types. A variable of a value type contains an instance of the type. This differs from a variable of a reference type, which contains a reference to an instance of the type. By default, on assignment, passing an argument to a method, or returning a method result, variable values are copied. In the case of value-type variables, the corresponding type instances are copied.

Normally you would create this as a property and set it accordingly

Given 

public class Bar 
{

     public Bar(int foo) => Foo = foo;

     public int Foo {get;set;}

     public void WriteLine() => Console.WriteLine(Foo);

     ...

Usage

public void Execute()
{

    var bar = new Bar(1);

    // set the property instead
    bar.Foo = 2;

    bar.WriteLine();

    ...

Upvotes: 2

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