Help with Deque - ostream_iterator

[lordmat]

Hey guys need a little help with the STL and ostream_iterator.

I've commented the code which isn't doing what I think it should do.

I tried using virtual in the base class for the operator but that just led to errors.

#include <iostream>
#include <iterator>
#include <deque>
using std::cin;
using std::cout;
using std::endl;
using std::ostream;

class Base{
public:
	Base(int foo = 5): test(foo){}
	friend ostream& operator<<(ostream &stream, const Base &obj){
		stream << obj.test << endl;
		return stream;
	}
	int return_test()const{return test;}
private:
	int test;
};

class Dervied : public Base{
public:
	Dervied(): Base(5){cha = 'a';}

	friend ostream& operator<<(ostream &stream, const Dervied &obj){
		stream << obj.return_test() << " " << obj.cha;
		return stream;
	}

private:
	char cha;
};

class Dervied2 : public Base{
public:
	Dervied2(): Base(5){cha = 'z';}

	friend ostream& operator<<(ostream &stream, const Dervied2 &obj){
		stream << obj.return_test() << " " << obj.cha;
		return stream;
	}
private:
	char cha;
};


int main(){
	std::deque<Base> test;

	Dervied one;
	Dervied2 two;

	test.push_back(one);
	test.push_back(two);
	
        // Need this to use Dervied and Dervied2 operator<<
	std::copy(test.begin(),test.end(),std::ostream_iterator<Base>(cout, " "));
		
	cin.get();
	return 0;
}

So what I want to happen is that it uses the Dervied and Dervied2 operator<<'s to show what is in the object yet it just uses the Base class instead.

Thanks guys.

[hanst99]

It doesn't work that way. I'd suggest you to write just one ostream<< operator for the base class, that uses a protected virtual method printOn(ostream), and you override the printOn method in the derived class.

[lordmat]

Thank you hanst99 for the help worked perfectly.