Issues with overloading the << operator - c++11

Question

I'm currently trying to playaround with operator overloading and built the following code
//Circle.cpp
//Circle.cpp
#ifndef CIRCLE_H
#define CIRCLE_H
#include "IOD.cpp"
#include<string>
class IOD; //Forward declaration
class Circle
{
public:
void display(IOD& ioDevice) const
{
ioDevice<<*this;
}
};
#endif
//IOD.cpp
//IOD.cpp
#ifndef IOD_H
#define IOD_H
#include <iostream>
#include<string>
#include "Circle.cpp"
class Circle; //Forward declaration
class IOD
{
// Interface for displaying CAD objects
public:
void operator<<(const Circle& c)
{
std::cout << "Displaying the object Circle Using IODevice GraphicsScreen for circles";
}
};
#endif
//Source.cpp
//Source.cpp
#include <iostream>
#include "Circle.cpp"
#include "IOD.cpp"
int main()
{
Circle* c1 = new Circle();
IOD* d1 = new IOD();
c1->display(*d1);
}
I'm trying to have the display function in Circle to call the overloaded operator << in IOD to print output about the Circle object to the screen. My understanding is that using "ioDevice<<*this" inside the display function should produce the desired output. But instead i'm getting the following error
error C2676: binary '<<': 'IOD' does not define this operator or a conversion to a type acceptable to the predefined operator
Any workarounds to this?

Answer 1

You have circular dependency between files: Circle.cpp includes IOD.cpp and vice versa.
In order to make it work fine you should split your cpp files into cpp and .h where .h will include only API definitions.
You should think of #include as "copy-paste".