IDK: C++ Rule of Three, and std::vector.

output.txt

Construct some objects:
Constructor 1
Constructor 2
Constructor 3

Do some assignment:
Assignment of Foo#1 to Foo#3

Copy-constructor?
Copy Constructor Foo#4 from Foo#2

Some vector stuff:
Copy Constructor Foo#5 from Foo#1
Copy Constructor Foo#6 from Foo#2
Copy Constructor Foo#7 from Foo#5
Destructor Foo#5
Get value from vector:
Copy Constructor Foo#8 from Foo#7
Retrieved value is 1

Can we use pointers instead?
Get value from vector:
Retrieved value is 1

Destructor Foo#8
Destructor Foo#7
Destructor Foo#6
Destructor Foo#4
Destructor Foo#3
Destructor Foo#2
Destructor Foo#1

ruleofthree.cpp

#include <iostream>
#include <vector>

using namespace std;

class Foo {
public:
    Foo(int n) {
        numObjects++;
        id = numObjects;

        cout << "Constructor " << id << endl;
        value = n;
    }

    // Copy-Constructor
    Foo(const Foo& other) {
        numObjects++;
        id = numObjects;

        cout << "Copy Constructor Foo#" << id << " from "<< other << endl;
        value = other.value;
    }

    // Destructor
    ~Foo() {
        cout << "Destructor Foo#" << id << endl;
    }

    // Copy Assignment operator
    Foo& operator=(const Foo& other) {
        cout << "Assignment of " << other << " to Foo#" << id << endl;
        value = other.value;
        return *this;
    }

    int data() {
        return value;
    }

private:
    friend ostream& operator<< (ostream& os, const Foo& foo) {
        os << "Foo#" << foo.id;
        return os;
    }

    int value;
    int id;
    static int numObjects;
};

int Foo::numObjects = 0;


int main() {
    cout << "Construct some objects:" << endl;
    Foo f1(1);
    Foo f2(2);
    Foo f3 = Foo(3);
    cout << endl;

    cout << "Do some assignment:" << endl;
    f3 = f1;
    cout << endl;

    cout << "Copy-constructor?" << endl;
    Foo f4(f2);
    cout << endl;

    cout << "Some vector stuff:" << endl;
    vector<Foo> fooVec;
    fooVec.push_back(f1);
    fooVec.push_back(f2);
    cout << "Get value from vector:" << endl;
    Foo f5 = fooVec[0];
    cout << "Retrieved value is " << f5.data() << endl;
    cout << endl;

    cout << "Can we use pointers instead?" << endl;
    vector<Foo*> fooRefVec;
    fooRefVec.push_back(&f1);
    fooRefVec.push_back(&f2);
    cout << "Get value from vector:" << endl;
    Foo* f6 = fooRefVec[0];
    cout << "Retrieved value is " << f6->data() << endl;
    cout << endl;

    return 0;
}

http://stackoverflow.com/questions/1361139/c-vector-of-pointers-to-objects
Discussion of std::unique_ptr

http://stackoverflow.com/questions/817263/is-it-possible-to-create-a-vector-of-pointers
Good comments about this issue, for a question asked by a newbie.