java代码：

package test.extend;

public  class Base {
	public Base(){
		System.out.println("基类构造");
		say();
	}
	
	public void say(){
		System.out.println("我是基类");
	}
	
	public static void main(String[] args) {
			Base base=new Child();
			
		}
}

 class Child extends Base{
	 public Child(){
		 System.out.println("子类构造");
		 say();
	 }
	 
	 @Override
	 public void say(){
		 System.out.println("我是子类");
	 }
}

运行结果:

基类构造
我是子类
子类构造
我是子类

 

 

 

 

 

 

在C#中：

 public class BaseA
    {
      public  BaseA()
        {
            Function();
        }

       public virtual void Function()
        {
           Console.WriteLine("Base::Function");
        }
    }

    class ChildA :BaseA
    {
      public  ChildA()
        {
            Function();
        }

        public virtual void Function()
        {
            Console.WriteLine("Child::Function");
        }
    }
    

运行结果：

Base:Function

Child::Function

 

在C++中:

  class BaseA
    {
        BaseA()
        {
            Function();
        }

        virtual void Function()
        {
           cout<<"Base::Function";
           cout<<endl;
        }
    }

    class ChildA : public BaseA
    {
        ChildA()
        {
            Function();
        }

        virtual void Function()
        {
            cout<<"Child::Function";
            cout<<endl;
        }
    }

        }
    }

运行结果：

Base:Function

Child::Function