Subclass objects in one array?

[ImNotaBot]

Hi

i want to save similar objects, meaning having same superclass, in an array. Example: I have a superclass vehicle. Class car and truck inherit from vehicle. Now i have a few from both of them an want to put them in an array, vector, set or else. Is this possible in C++ or are there an workarounds? When i remember right, Java and C# offer this feature.


Here again an example:

class vehicle{
  int mMaxSpeed;
}
class truck : public vehicle{
  int mTrailerLength;
}
class car : public vehicle{
  bool mHasHitch;
}

main()
{
  truck mytruck = new truck();
  car mycar = new car();

  vector<vehicle> myCarPool;
  myCarPool.pushback(mytruck);
  myCarPool.pushback(mycar);
}

Greets

[S_M_A]

You can't store objects of different classes into a vector but you can store a base pointer. To avoid having memory leaks due to forgotten deletes you can make the vector store a smart pointer like boost::shared_ptr http://www.boost.org/doc/libs/1_50_0...shared_ptr.htm or std::shared_ptr if your compiler supports them. http://en.cppreference.com/w/cpp/memory/shared_ptr

[VictorN]

... Besides, your "syntax" for new and main() looks like to be incorrect. Did you probably mean:

int main()
{
  truck* mytruck = new truck();
  car* mycar = new car();

  vector<vehicle*> myCarPool;
  myCarPool.pushback(mytruck);
  myCarPool.pushback(mycar);
  ...

  delete mycar ;
  delete mytruck;
  return 0;
}

[D_Drmmr]

Here again an example:

Note that the vehicle class must have a virtual destructor if you want to store (and ultimately delete, I presume) derived instances using a pointer to the base class.

You can also have a look at the Boost Pointer Container Library.

[JohnW@Wessex]

When i remember right, Java and C# offer this feature.

The method that Java and C# use is similar, under the hood, to what you do in C++.

There is not actually much difference between the concepts of Java & C++.
Both have containers that store one type of object.

In Java, you can only store references to objects in a container.

In C++ you store copies of objects in a container. The difference being that is that the objects stored could be pointers.

vector<car>    myCars; // A vector of 'car' objects. The 'car's are stored in the vector. No equivalent in java.
vector<car *> myPointerCars; // A vector of pointers to 'car' objects. The 'car's are stored elsewhere.

[ImNotaBot]

Well sorry that I did not answer. Quite impolite... but I am terribly under pressure of time due to exams.
I will come back to the topic as soon as i made them.

I really appreciate your help so thanks to all of you.

@ VictorN: Yes your right :-D i just wrote it down for a quick sloppy illustration of the problem.