Overriding default value in derived class (c#)

Question

If i have an accessor and default property in a base class as follows:

class base{
protected int _foo = 5;
public int foo {get{return _foo;}set{_foo = value;}}
}

Then I derive this class, is it possible to override the default value of _foo?

class derived:base{
// foo still returns 5?
protected new int _foo = 10;
}

Answer 1

The _foo = 5 statement effectively executes in the base class's constructor. You can add code to the derived class constructor that changes foo's value immediately afterwards:

class derived:base{
    public derived()
    {
        foo = 10;
    }
}

Answer 2

You can create a property:

protected virtual int _foo { get { return 5; } }

and

protected override int _foo { get { return 10; } }

Answer 3

You could use a construtor to initialise the derived class and set the base types _foo property:

class derived:base
{
    public derived()
    {
        this._foo = 10;
    }
}