beginer with class-someone can help-me

Question

i'm beginning learn class and i done this simple code but i don't know where i went  wrong   someone can help-me

 
using System; 
 
public abstract class A 
{ 
 public string _a;
 string _b; 
 
 public string a 
 { 
  get { return _a; } 
 set { _a = value; } 
 } 
 
 public virtual void f1() 
 { 
 Console.WriteLine(_a); 
 } 
 
 public abstract void f2(); 
} 
 
public class B : A 
{ 
 string _b; 
 
 public string b 
 { 
  get { return _b; } 
  set { _b = value; } 
 } 
 
 public void B()
 {     
         base._b = "boo";
 } 
 
 public void f2() 
 { 
 Console.WriteLine(_b); 
 } 
} 
 
public class Program
{ 
 static void Main() 
 { 
 B objeto = new B(); 
 
 objeto.a = "aaa"; 
 objeto.b = objeto.a; 
 objeto.f1(); 
 objeto.f2(); 
 } 
} 
 

Answer 1

Use the following code insted of your code

Problems :

1. In Class A you had neglected to provide access specifier "public" to _b

2.In class B you should not add a return type to your constructor so remove the "void" keyword

3. You did not overide f1 in class B

4. You did not use keyword "override" while declaring f2() in class B

public abstract class A
    {
        public string _a;
        public string _b;

        public string a
        {
            get { return _a; }
            set { _a = value; }
        }

        public virtual void f1()
        {
            Console.WriteLine(_a);
        }

        public abstract void f2();
    }

    public class B : A
    {
        string _b;

        public string b
        {
            get { return _b; }
            set { _b = value; }
        }

        public B()
        {
            base._b = "boo";
        }

        public override void f1()
        {
            base.f1();
        }



        public override void f2()
        {
            Console.WriteLine(_b);
        }
    }

Answer 2

In class A, change

string _b;

to

public string _b;

---

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Answer 3

You didn't clarify what your problem was.  The biggest thing I see is that you have defined a field (_b) in your base class but never use it.  Therefore it should be removed. 

f2 in derived type B needs to be marked with override because you're overriding the abstract method in A.  You should have gotten a warning about defining a new method with the same name.

Michael Taylor
http://msmvps.com/blogs/p3net

Answer 4

thanks. i will remember of this in the next exercise.

Answer 5

thanks!

Answer 6

thanks!