Question

I’m trying to understand base constructor implementation. Consider this situation
If I have base class Sport

public class Sport 
{
   public int Id { get; set; }
   public string Name { get; set; }

   public Sport() 
   {
      Console.WriteLine("Sport object is just created");
   }

   public Sport(int id, string name) 
   {           
      Console.WriteLine("Sport object with two params created");
   }
}

Now I have basketball class which inherhit Sport class and I want to on basketball object initialization to use second constructor with two params.

public class Basketball : Sport
{    
    public Basketball : base ( ???? )
    {
       ?????
    }
}

First I was thinking to use private fields int _Id and string _Name and to use them in the constructor call

public Basketball : base ( int _Id, string _Name )
{
   Id = _Id;
   Name = _Name;
}

But that doesn’t make sense of using inheritance, so please explain me on this example.

Updated
Thanks everyone, I’m using code like this and it’s ok.

public Basketball(int id, string name) : base (id, name)
{
   Id = id;
   Name = name;
}

Just to make sure, On this line public Basketball(int id, string name) : base (id, name) I’m declaring variables id, name, since my original are Capitalized vars, and using as params on base (id, name) to hit my base contructor.

Thank everyone., very helpful/

Answer 1

You have to pass values or variables of the derives class to the base class constructor if the base class constructor does not have any default parameterless constructor.

You dont need to declare anything in the base constructor call

The main purpose of base keyword is to call the base class constructor.

In general,if you do not declare any constructor of your own,the compiler creates a default constructor for you.

But if you define your own constructor having parameter,then the compiler does not create the default parameterless constructor.

So in the case where you dont have a default constructor declared in the base class and want to call a base class constructor having parameters,you have to call that base class constructor and pass the required values through base keyword

Do it like this

public Basketball() : base (1,"user")

OR

public Basketball(int id,string n) : base (id,n)

OR

public Basketball(int id,string n) : base ()

OR

public Basketball() : base ()

is similar to

public Basketball()//calls base class parameterless constructor by default

It all depends on how you want your class to behave when the derived class is instantiated