C＃的子类中父类的构造方法

Question

I have one parent class and one child class. The parent has a constructor that initializes its parameters.

My question is: How does the child look to the parent's constructor? Can I define a constructor for the children?

Answer 1

This inheritance sample shows:

• how to call the parent constructor from a new constructor on the child
• how to pass parameters required by the parent constructor

Code sample:

public class Parent
{
    private object _member;

    public Parent(object member)
    {
        this._member = member;
    }
}

public class Child : Parent
{
    public Child(object member)
        : base(member)
    {
    }
}

Answer 2

you can use base(...) in ctor of your child class.

foreacmple:

public class Child : BaseClass 
{
    public Child() : base(/*some parameters*/) //CALLING BaseClass parametrized ctor
    {  
    }
}

Just note, if you don't need some specific parameters, just do not do anything , cause BaseClass default ctor will be called by the way when you call ctor of a Child class.

Answer 3

You have to define constructors for the children. You can call the base class' constructor using : base() between the constructor prototype and its implementation:

public class Parent {
  public Parent() {
    ...
  }
}

public class Child : Parent {
  public Child() : base() { // calls Parent.ctor
  }
}

Answer 4

Of course.

You are after the "base" keyword.

public class Fruit
{
    string TypeOfFruit { get; set; }

    public Fruit (string typeOfFruit)
    {
        TypeOfFruit = typeOfFruit;
    }

}

public class Apple : Fruit
{
    string AppleType { get; set; }

    public Apple(string appleType) : base("Apple")
    {
        AppleType = appleType;
    }

}

Answer 5

You can very well define a constructor for the child class the default one is provided only in case when you do not define a constructor for a class

Meanwhile for how to look up for the constructor of parent

It would check for a parameterless constructor to be present in the parent class and in case you do not have one ( well the compiler lets you know the same) or else you will have to call the parent constructor with the parameters like base("This is the string parameter")

If you meant something else please update the question.