Passing parameters to the base class constructor

Question

If the base class and derived class both have their constructors with parameters then where we pass the parameters to the base class constructors?

This is a duplicate question. http://stackoverflow.com/questions/12051/calling-base-constructor-in-c-sharp Googling "base class constructor parameters" would have brought it right to you. — catfood, May 05 '14 at 20:59
You say "you can't instantiate an abstract class," but that's not entirely true. If you create an instance of the non-abstract derived class, that instance is also an instance of the abstract base class. It is also an instance of the System.Object class. — phoog, May 05 '14 at 21:05
FYI, even if it's an `abstract` class, it can have defined custom constructors with parameters that can be passed in. They can't be instantiated/called _directly_ but instead are referenced in derived types by using the [`base` keyword](http://msdn.microsoft.com/en-us/library/hfw7t1ce.aspx) with the derived constructors. — Chris Sinclair, May 05 '14 at 21:05

score 62 · Accepted Answer · answered May 05 '14 at 20:49

62

Like this:

public class DerivedClass : BaseClass
{
    public DerivedClass(int derivedParam, String baseParam):base(baseParam)
    {
    }
}

The base keyword here calls the base class constructor that matches the provided parameter overload.

answered May 05 '14 at 20:49

BradleyDotNET

Is the default constructor still invoked if base constructor is called as `:base(param)` ? – vhmvd Jun 08 '20 at 05:48
No. That constructor would have to call `this()` @Ahmn21 – BradleyDotNET Jun 10 '20 at 22:49

1 Answers1