creating an array which can hold objects of different classes in C++

Question

Hi,

How can i create an array which can hold objects of different classes in C++.

Answer 1

You can use boost::any or boost::variant (comparing between the two: [1]).

Alternatively, if the "objects of different classes" have a common ancestor (say, Base), you could use a std::vector<Base*> (or std::vector<std::tr1::shared_ptr<Base> >), and cast the result to Derived* when you need it.

Answer 2

define an base class and derive all your classes from this.

Then you could create a list of type(base*) and it could contain any object of Base type or derived type

Answer 3

Have a look at boost::fusion which is an stl-replica, but with the ability to store different data types in containers

Answer 4

If you want to create your own, wrap access to a pointer/array using templates and operator overloading. Below is a small example:

#include <iostream>

using namespace std;

template <class T>
class Array
{
private:
    T* things;

public:

    Array(T* a, int n) {
        things = new T[n];
        for (int i=0; i<n; i++) {
            things[i] = a[i];
        }
    }

    ~Array() {
        delete[] things;
    }

    T& operator [](const int idx) const {
        return things[idx];
    }
};

int main()
{    
    int a[] = {1,2,3};
    double b[] = {1.2, 3.5, 6.0};

    Array<int> intArray(a, 3);
    Array<double> doubleArray(b, 3);

    cout << "intArray[1]: " << intArray[1] << endl;
}