How to create class objects dynamically?

Question

Let\'s say I have a class box, and a user can create boxes. How to do it? I understand I create objects by className objectName(args); but how

Answer 1

The following factory method creates Box instances dynamically based on user input:

class BoxFactory
{
  public:
    static Box *newBox(const std::string &description)
    {
      if (description == "pretty big box")
        return new PrettyBigBox;
      if (description == "small box")
        return new SmallBox;
      return 0;
    }
};

Of course, PrettyBigBox and SmallBox both derive from Box. Have a look at the creational patterns in the C++ design patterns wikibook, as one of them probably applies to your problem.