How to Set BASE CLASS with value

With apologies to patel_vijay for expanding on his solution ...

Quote:

Or you can acess the base class properties in deried class using this or base keyword.

here is an example...
Say you have something set up like

public class OldCar
{
    protected int aHiddenProp;
    public int AHiddenProp
    {
      get { return aHiddenProp; }
      set { aHiddenProp = value; }
    }
}
public class NewCar : OldCar
{
    // This class adds some stuff to OldCar e.g.
    private bool _isAirBag;
    public bool IsAirBag
    {
        get { return _isAirBag; }
        set { _isAirBag = value; }
    }
    public string showValues()
    {
        base.AHiddenProp = 4; // change the value in the base class
        return _isAirBag.ToString() + ' ' + base.AHiddenProp.ToString();
    }
}

then anything creating an instance of the NewCar class can use the underlying base class properties as well...

private void button1_Click(object sender, EventArgs e)
{
    NewCar nc = new NewCar();
    nc.AHiddenProp = 3;         // this is actually in the base class
    nc.IsAirBag = true;
    MessageBox.Show(nc.showValues());
}

The messageBox will display "True 4" because I've adjusted the value in the showValues function

[Edit]
If you (really) want to pass an instance of OldCar to NewCar then you will have to write an appropriate constructor for NewCar e.g.

public NewCar() { }
public NewCar(OldCar oc)
{
    this.AHiddenProp = oc.AHiddenProp;
    // copy all of the values passed in oc to this instance
}

but the better route is just to use NewCar in the first place.

See also http://msdn.microsoft.com/en-us/library/ms173149.aspx[^]