How to port Java interface codes into C++ abstract base class? -

im new in oop programming , c++ , im learning design patterns.

just grab head first design patterns book learn from. great , im getting hold basic concepts.the first chapter talks programming interface rather implementation. unfortunately me though, examples uses java.

below java code sample books using "interface", understand cannot directly ported in c++. ive tried implement c++'s abstract base class. im lost in setting quackbehavior dynamically.

can c++ virtual functions definition dynamic? can please show me how best way port java code c++? need sure im on right track in learning oop. thanks!

//flybehavior.java public interface flybehavior{     public void fly(); //the interface flying behavior classes implement }   public class flywithwings implements flybehavior {     public void fly(){         system.out.println("im flying!"); //flying behavior implementation ducks fly     } }  //quackbehavior.java public interface quackbehavior{     public void quack(); }  public class quack implements quackbehavior {     public void quack() {         system.out.println("quack");     } }  public class squeak implements quackbehavior {     public void quack() {         system.out.println("squeak");     } }  public class mutequack implements quackbehavior {     public void quack() {         system.out.println("<<silence>>");     } }    //duck.java public abstract class duck{     flybehavior flybehavior;     quackbehavior quackbehavior;     public duck(){     }      public abstract void display();      public void performfly(){         flybehavior.fly();     }      public void performquack(){         quackbehavior.quack();     }      public void setflybehavior(flybehavior fb){         flybehavior = fb;     }      public void setquackbehavior(quackbehavior qb){         quackbehavior = qb;     }      public void swim(){         system.out.println ("all duck float, decoys");     } }   //mallardduck.java public class mallardduck extends duck{     public mallardduck(){         quackbehavior = new quack();         flybehavior = new flywithwings();     }      public void display(){         system.out.println("im real mallard duck");     } }  //miniducksim.java public class miniducksimulator{     public static void main (string[] args){         duck mallard = new mallardduck();          mallard.setquackbehavior(new squeak()); // im lost                                                 //how can definition of virtual functions in c++ dynamic?          mallard.performquack();         mallard.performfly();     } } 

dang - should have known head first gang port it. anyway here's 1 solution:

   // headfirst.cpp : defines entry point console application.    //     #include "stdafx.h"     class quackbehavior    {    public:       virtual void quack() = null;    };     class quack : public quackbehavior    {    public:       void quack()       {          printf("quack");       }    };     class squeak : public quackbehavior    {    public:       void quack()       {          printf("squeak");       }    };     class duck    {    public:       quackbehavior *pquack;        void performquack()       {          if (pquack!=null)             pquack->quack();       }        void setquackbehavior(quackbehavior *qb)       {          pquack = qb;       }    };     class mallardduck : public duck    {    public:       mallardduck()       {          pquack = new quack();       }    };     int _tmain(int argc, _tchar* argv[])    {       duck *mallard = new mallardduck();       mallard->setquackbehavior(new squeak());       mallard->performquack();    return 0;    }