Stream function compile problem

[Know_Your_Role]

Hi all

Can anyone help me? I'm having a compile problem when attempting to compile code including declaration and definition of the following:

ostream& operator << (ostream& output, const Dog& theDog);
friend ostream& operator << (ostream& output, const Dog& theDog);

The compiler (Visual Express 2008) keeps telling me that it cannot find the return type (int assumed - C++ does not support default int etc). Obviously I'm intending for the return type to be ostream&.

Can anyone work out what's going on here? I am including "using std:stream" at the start of the program.

Cheers! :-)

[laserlight]

Post the smallest and simplest program that demonstrates the error.

[Know_Your_Role]

Hi

I have included the whole dog class. Note that this is the first part of three C++ files that make up my project...

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

class Dog
{
public:
	Dog ();
	Dog (int);
	~Dog ();

	int getAge () const {return itsAge;}
	void setAge (int age) {itsAge = age;}

	friend ostream& operator << (ostream& output, const Animal& theAnimal); 

private:
	int itsAge;
};

Dog::Dog () : itsAge(0)
{
	cout << "Dog default constructor...";
}

Dog::Dog (int age) : itsAge (age)
{
	cout << "Dog constructor with parameter...";
}
Dog::~Dog()
{
	cout << "Destructed a dog :-(...";
}
ostream& operator << (ostream& output, const Dog & rhs) 
{
	output << rhs.getAge();
	return output;
}

Cheers :-)

[laserlight]

Well, one obvious problem is that you declared the overloaded operator<< as:

friend ostream& operator << (ostream& output, const Animal& theAnimal);

but the name Animal has not been declared at that point. You probably want to declare it as a non-member non-friend function:

ostream& operator << (ostream& output, const Dog& theAnimal);

Other than that, it looks okay, but:

• You #include <iostream> because you use std::cout to print some text to help you see how the constructors and destructor work. This is fine, but you should #include <ostream> as well because when you do remove the printing of those text, you should then remove <iostream> from the list of files included.
• Do not use using declarations (e.g., using std::cin) in a header file except within some restricted scope.
• Declare the constructor that takes an int as explicit since it probably does not make sense to write: Dog dog = 10;