C# global variables unchangeable outside of locality?-CodePudding

Variables declared and initialized in Main, are not able to be changed through methods belonging to other classes. This is extremely unintuitive and there must be a way around this.

Anyone know why, and how to solve? Or am I not understanding something fundamental about inheritance.

Screenshot of code and result

TestClass stuff = new TestClass();

int test = 1;

Console.WriteLine("This is an integer: {0}\nAnd this is an amount it's added with: 2", test);

stuff.ChangeVariable(test);

Console.WriteLine("\nand it's {0} here! Why doesn't the change stick!?", test);

class TestClass
{
    public void ChangeVariable(int item)
    {
        item  = 2;your text
        Console.WriteLine("\nFor some reason, 'item' here is {0},", item);
    }
}

CodePudding user response：

You are not understanding something fundamental.

Your code doesn't use inheritance. Your code has two classes but they don't inherit. You are using an implicit Main method that belongs to a class and you are defining a class named TestClass. These two classes have no relation to each other.

There are no global variables in C#. int test is a local variable in the implicit Main method.

int is a value type, not a reference type. When you pass test to the ChangeVariable() method, the value of test is passed but not a reference to the test variable. The changes made to item are limited to the ChangeVariable() method.

CodePudding user response：

If you don't use the ref keyword, it won't change the variable in the other class. https://learn.microsoft.com/en-us/dotnet/csharp/language-reference/keywords/ref

So if you want it to change the variable, your code should look like this:

using System;

TestClass stuff = new TestClass();

int test = 1;

Console.WriteLine("This is an integer: {0}\nAnd this is an amount it's added with: 2", test);

stuff.ChangeVariable(ref test);

Console.WriteLine("\nand it's {0} here! Why doesn't the change stick!?", test);

class TestClass
{
    public void ChangeVariable(ref int item)
    {
        item  = 2;
        Console.WriteLine("\nFor some reason, 'item' here is {0},", item);
    }
}