How to use sub class attribute in C#

Question

Program

using System;

namespace ConsoleApp4
{
    class Program
    {
        static void Main(string[] args)
        {
            B x = new B();
            x.show();
        }
    }

    public class A     //base class
    {
        protected int no = 1;

        public void show()
        {
            Console.WriteLine(no);
        }
    }
    public class B : A  //sub class
    {
        protected int no = 100;
    }
}

Output 1

How do I use sub Class attribute value instead of base class attribute value?

I tried override, new keywords and it doesn't seem to work.

What I have learned regarding this question is: sub class holds both parent class attribute, and its own attribute.

But sub class attribute get hide by base class attribute, if it is intentional you can use new keyword.

Thank you

You don't put `no` in the subclass; it already has an accessible `no` from the base class. Also, please name your methods PascalCaseLikeThis, rather than camelCaseLikeThis — Caius Jard, Mar 08 '21 at 16:30
I'm telling you not to put `no` in the subclass. Call it something else — Caius Jard, Mar 08 '21 at 16:33
Read this: https://stackoverflow.com/questions/1922550/new-modifier-in-c-sharp — Mario Vernari, Mar 08 '21 at 16:35
`no` is a field and cannot, therefore, be overridden. If your intention is to have a different initial value in the subclass, then move the initialisation to the constructor. — Johnathan Barclay, Mar 08 '21 at 16:35
Another option is to make it a virtual property that you can override in the derived class. — juharr, Mar 08 '21 at 16:36
Why do you want to override class field? If you want to do it try with properties instead of fields. — zolty13, Mar 08 '21 at 16:37
thank you every one . i havent learnt about field . looking forward to it — , Mar 08 '21 at 16:42

score 3 · Accepted Answer · answered Mar 08 '21 at 16:35

how to Use sub class attriubute in C#

protected int no = 1;

This is not an attribute, it's a field.

You can either reassign that field's value in the subclass (fiddle):

public class B : A  //sub class
{
    public B() 
    {
        no = 100; 
    }
}

Or you can replace your field with a property, which can be virtual and, thus, overridden (fiddle):

public class A     //base class
{
    protected virtual int no => 1;

    public void show()
    {
        Console.WriteLine(no);
    }
}
public class B : A  //sub class
{
    protected override int no => 100;
}

score 1 · Answer 2 · answered Mar 08 '21 at 16:37

Do not declare no field in class B. You can access no from contructor or method.

By declaring no in class B you are hiding no in class A. I suggest not to use same names for fields in inherited classs. By using protected you can access no field from both classes.

public class A     //base class
{
    protected int no = 1;

    public void show()
    {
        Console.WriteLine(no);
    }
}
public class B : A  //sub class
{
    public B()
    {
        no = 2;
    }
}

How to use sub class attribute in C#

2 Answers2