Correct use of Friend for operator overloads in header file

[maddav]

Hi,
Recently (today) got an assignment to take a particular code that we've done previously, and split it into 3 files: 2 .cpp files and a header file. Now, i believe i've done it correctly, but the only thing that's throwing up errors is the use of friend for overloading the << operator.

Here's how it was used in the previous example (class name is "complex"):

...//other class stuff
friend ostream & operator<<(ostream &os, const complex &z);
}; //end of class

ostream & operator<<(ostream &os, const complex &z)
{
	//..stuff...
}

and I've split the class declaration and function definitions across the header file and one of the .cpp files respectively, such that the header file contains this:

#ifndef COMPLEX_H
#define COMPLEX_H

using namespace std;

namespace ns1 
{
	const double pi = 3.141592;
	
	class complex
	{
		
		
	private:
		
		double re;
		double im;
		
	public:
		
		complex(){re=0; im=0;}
		complex(double real, double imag){re=real;im=imag;}
		~complex(){;}
		double getreal() const;
		double getimag() const;
		double getmod();
		double getmod2() const;
		complex getconj() const;

		complex operator+ (const complex &z) const;
		
		friend ostream & operator<<(ostream &os, const complex &z);
	};
}

#endif

and the .cpp file contains this:

#include<iostream>
#include<cstdlib>
#include<cmath>
#include "head.h"

using namespace std;
using namespace ns1;

double complex::getreal() const {return re;}
double complex::getimag() const {return im;}
double complex::getmod() {return sqrt(re*re + im*im);}
double complex::getmod2() const {return (re*re+ im*im);}
complex complex::getconj() const {complex temp(re,im*-1);return temp;}

complex complex::operator+ (const complex &z) const {complex temp(re+z.getreal(),im+z.getimag());return temp;}

ostream & operator<<(ostream &os, const complex &z)
{
	if(z.im==0)	{os<< z.re; return os;}
	else{
		if(z.im>0)	{os<< z.re << "+"<< z.im << "i"; return os;}
		else		{os<< z.re << z.im << "i"; return os;}
		}
}

Yet I'm getting the errors that would indicate because the data it's trying to access is private (i.e. z.re) it cannot use it, so it's not getting friended at all.

Could anyone let me know if this looks alright, and what could be going wrong (oh and I've tried moving the friend declaration outside of public and private to no avail.)

btw I'm using Xcode 3.2.1 if that's of any relevance

Thanks!

[corby]

in ur .h file u need to do something like this:

class Complex
{
	friend ostream &operator<<( ostream &, const Complex & );
	friend istream &operator>>( istream &, Complex & );
public:
//ur stuff
private:
//ur stuff
};

u should declare the input and ouput operators as friends of the class, not only one

[maddav]

I don't see how that would make any difference, and upon trying it, it doesn't.

[kvprajapati]

The source (.cppp) definition must be placed inside the namespace block.

#include<iostream>
#include<cstdlib>
#include<cmath>
#include "head.h"

using namespace std;

namespace ns1 {

double complex::getreal() const {return re;}
double complex::getimag() const {return im;}
double complex::getmod() {return sqrt(re*re + im*im);}
double complex::getmod2() const {return (re*re+ im*im);}
complex complex::getconj() const {complex temp(re,im*-1);return temp;}

complex complex::operator+ (const complex &z) const {complex temp(re+z.getreal(),im+z.getimag());return temp;}

ostream & operator<<(ostream &os, const complex &z)
{
	if(z.im==0)	{os<< z.re; return os;}
	else{
		if(z.im>0)	{os<< z.re << "+"<< z.im << "i"; return os;}
		else		{os<< z.re << z.im << "i"; return os;}
		}
 }
};

OR you may qualify each definition separately.

......
double ns1::complex::getreal() const {return re;}
double ns1::complex::getimag() const {return im;}
double ns1::complex::getmod() {return sqrt(re*re + im*im);}
double ns1::complex::getmod2() const {return (re*re+ im*im);}
ns1::complex ns1::complex::getconj() const {complex temp(re,im*-1);return temp;}

ns1::complex ns1::complex::operator+ (const complex &z) const {complex temp(re+z.getreal(),im+z.getimag());return temp;}

ostream & ns1::operator<<(ostream &os, const complex &z)
{
	if(z.im==0)	{os<< z.re; return os;}
	else{
		if(z.im>0)	{os<< z.re << "+"<< z.im << "i"; return os;}
		else		{os<< z.re << z.im << "i"; return os;}
		}
}

[maddav]

Thanks! That was all it needed!