Inheritance with base class constructor with parameters [duplicate]

Answer 1

I could be wrong, but I believe since you are inheriting from foo, you have to call a base constructor. Since you explicitly defined the foo constructor to require (int, int) now you need to pass that up the chain.

public bar(int a, int b) : base(a, b)
{
     c = a * b;
}

This will initialize foo's variables first and then you can use them in bar. Also, to avoid confusion I would recommend not naming parameters the exact same as the instance variables. Try p_a or something instead, so you won't accidentally be handling the wrong variable.

Answer 2

The problem is that the base class foo has no parameterless constructor. So you must call constructor of the base class with parameters from constructor of the derived class:

public bar(int a, int b) : base(a, b)
{
    c = a * b;
}