OO 101

hi,

im trying to set a base class property value from child class using C#, is that possible

public class B : A
{
 const int i = 1; // i want to set the base i to 1
}
public class A
{
 int i;
 int j;
 A()
 {
 y = i; // here i want y to be 1
 }
}

what should i do .. virtual.. !!?declare i as protected then simply set i in the subclass.

protected int i;

FYI, your B class is currently declaring a new field i. To use/set the i as I show above you will have to do that in a method, not in the subclasses (B) definition of fields.
so you're saying this will work?

class B : A
{
 B()
 {
 i = i +1;
 }
}
class A
{
 int i;
 A()
 {
 System.Console.Write(i);
 }
}

what's the ouput 0 or 1?
First of all the posted code will not work/compile it should be defined like this

public class B : A {
 public B() {
 i = i +1;
 //or a C# shortcut
 // i++;
 }
}
public class A {
 protected int i;
 public A() {
 System.Console.Write(i);
 }
}

Now if you execute this line of code somewhere

B b = new B();

When B is constructed the compiler see's that is derived from class A and will call A's default constructor so 0 will print to console. Now B's default constructor will be executed and i will be incremented by 1.

Since i is declared as protected it will only be available to B's internal methods, i.e., you cannot access i like this

int x = b.i;

Hope this helps.