Overloading << operator, separated implementation and decleration - c++

Question

I'm trying to overload << operator but I get an error which is below.
rollingDice.h|14|error: ‘std::ostream& rollingDice::operator<<(std::ostream&, const rollingDice&)’ must take exactly one argument|
Here is my code. I separated implementation and decleration. I think the problem occurs due to that because I coded same as so many web pages and Deitel&Deitel show.
rollingDice.cpp
#include <iostream>
#include <cstdlib>
#include <ctime>
#include <stdlib.h>
#include "rollingDice.h"
using namespace std;
rollingDice::rollingDice(unsigned int valN)
{
n=valN;
r=new int [n];
}
int rollingDice::length()
{
return n;
}
void rollingDice::generate()
{
srand48(time(NULL));
int i=0;
for (i=0; i<n; ++i)
{
r[i]=1+(lrand48()%6);
}
}
rollingDice& rollingDice::init(unsigned int valN)
{
n=valN;
r=new int [n];
return *this;
}
ostream& operator << (ostream& output, rollingDice& rd)
{
int temp=n;
if (temp>12)
temp=12;
int i=0;
for (i=0; i<temp; ++i)
{
output << rd.r[i] << " ";
}
return output;
}
double rollingDice::getAverage()
{
generate();
double total=0;
int i=0;
for (i=0; i<n; ++i)
total+=r[i];
total=total/double(n);
return total;
}
rollingDice.h
#ifndef rollingDice_H
#define rollingDice_H
#include <string>
using namespace std;
class rollingDice
{
public:
rollingDice(unsigned int n);
void generate();
rollingDice& init(unsigned int valN);
double getAverage();
int length();
ostream& operator << (ostream& output, const rollingDice& rd);
private:
unsigned int n;
int* r;
};
#endif
rollingDiceApp.cpp
#include <iostream>
#include "rollingDice.h"
using namespace std;
int main()
{
rollingDice r(16);
cout<<r.getAverage()<<endl;
cout<<r.length()<<endl;
r.init(8).generate();
cout<<r.getAverage()<<endl;
cout<<r.length()<<endl;
}

Answer 1

In the class definition add keyword friend to the operator declaration
friend ostream& operator << (ostream& output, const rollingDice& rd);
Otherwise the compiler consideres the operator as a member function with the first implicit parameter that corresponds to this
Also take into account that in the operator definition it seems you have to use
int temp=rd.n;
instead of
int temp=n;