virtual and dynamic? Superclass to Subclass

jaised (13)
Ok, I will do my best to explain my situation. I have tried looking online to try to make this work and have yet to find anything so I hope you can help me out. Thanks in advance!!!

So I have a Document class which contains a vector<DocComponent*>. These docComponents are things such as Text, Table, and Graphic objects. Each are child classes of DocComponent. In my Document class, I have a addElement method:

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void Document::addElement(DocComponent &component)
{
	// binary search and i-sort pg. 147
	components.push_back(&component);
}

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Therefore, it adds each type of object i.e. Text, Graphic, ect. Each of these classes has an overloaded operator<< method used to just display their variables. Below, I am trying to print out each object with their respectful overloaded operator<< method. However, it keeps calling the DocComponent's << method and not the respectful class.

For example I create and add each kind of child class objects to the document component array. When I print out the document it displays 1, 2, 3 (which is what the DocComponent << does) where it is actually supposed to each field.
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void main() {        
        Document d;
	Text* t = new Text(1, 2, 3, 4, 5, 6);
	Table* tbl = new Table(1, 2, 3, 4, 5, 6, 7);
	Graphics* g = new Graphics(1, 2, 3, 4, 5);
	d.addElement(*t);
	d.addElement(*tbl);
	d.addElement(*g);
	cout << d << endl;
}

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DocComponent << method:

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ostream& operator<<(ostream &s, DocComponent &doc)
{
	// formatting for output to the user via cout command
	s << "*DOC_COMPONENT*\n" << 
		"Top Margin (in inches): " << doc.top << "\n" <<
		"Left Margin (in inches): " << doc.left << "\n" <<
		"Right Margin (in inches): " << doc.right << "\n\n";
	return s;
}

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All 3 subclasses have similar << methods, but here is the example of Text:

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ostream& operator<< (ostream  &s, Text &t)
{
	s << "*TEXT*\n" <<
		"Top Margin (in inches): " << t.top << "\n" <<
		"Left Margin (in inches): " << t.left << "\n" <<
		"Right Margin (in inches): " << t.right << "\n" <<
		"Font Type: " << t.fontType << "\n" <<
		"Font Size: " << t.fontSize << "\n" <<
		"Number of Characters: " << t.noChars << "\n\n";
	return s;
}

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Below is the Document's << method:
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ostream& operator<< (ostream &s, Document &d)
{
	// display the Document's information via for-loop
	s << "*DOCUMENT*\n\n\n";

	// DocComponents
	s << "components vector\n"; 
	for(int i = 0; i < d.components.size(); i++)
	{
		s<< "\t" << *(d.components[i]);
		s << "\n";
	}
	s << "\n";
	return s;
}

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I read all around online and it said that it had to do something with virtual, but I cannot find a way to make << method both friend and virtual. Any help with this would be outstanding! Thank you for the help!
guestgulkan (2942)
You can't directly declare a virtual friend function.
But you can do this:
http://www.codeguru.com/forum/archive/index.php/t-365262.html
seymore15074 (449)
You could add a virtual print method to the base class, and overload it in each derived class. In the base class, define the operator << that calls the print method. Then, from a base class pointer, a call to operator << would result in the polymorphic print behavior that you are after.
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