Inheritence-example.cc

#include <cstdlib>
#include <iostream>
#include <vector>

#define NUM_TREES 5

using namespace std;

// base tree
class AbstractDecisionTree {
public:
    AbstractDecisionTree () {
        cout << "AbstractDecisionTree CTor" << endl;
    }
    
    virtual ~AbstractDecisionTree () {
        cout << "AbstractDecisionTree DTor" << endl;
    }
};

// derived tree
class DecisionTree : public AbstractDecisionTree {
public:
    DecisionTree () {
        cout << "DecisionTree CTor" << endl; 
    }
    
    virtual ~DecisionTree () {
        cout << "DecisionRree DTor" << endl;
    }
};

// base forest class
class Forest {
public:
    vector<AbstractDecisionTree*> absDTrees;
    
    Forest () {
        cout << "Forest CTor" << endl;
    }
    
    virtual ~Forest () {
        cout << "Forest DTor" << endl;
    }
};

// derived forest class
class RandomForest : public Forest {
public:
    RandomForest () {
        cout << "RandomForest CTor" << endl;
        for (int i = 0; i < NUM_TREES; i++) {
            cout << "Creating " << i << "(th) decision tree" << endl;
            DecisionTree* dtre = new DecisionTree();
            absDTrees.push_back(dtre);
        }
    }
    
    virtual ~RandomForest () {
        cout << "RandomForest DTor" << endl;
        for (int i = 0; i < NUM_TREES; i++) {
            cout << "Deleting " << i << "(th) decision tree" << endl;
            DecisionTree* dtre = dynamic_cast<DecisionTree*>(absDTrees[i]);
            delete dtre;
        }
    }
};

int main(int argc, char** argv) {
    cout << "Starting main program" << endl;
    RandomForest rf;
    cout << "End of main program" << endl;
    return 0;
}