friend not allowed outside of a class definition - c++

Question

I'm trying to ovrerload the cout operator in an assignment and I was forced and asked to split my class into (.h and .cpp). Here is my full code:
instructor.h
#include "person.h"
#ifndef instructor_h
#define instructor_h
class instructor: public person {
private:
int children;
int salary;
string maritalStatus;
public:
instructor();
instructor(string, string, string, int , int ,string);
instructor operator++();
void print();
int calcSalary();
int getSalary();
int getNumOfChildren();
string getMarialStatus();
friend ostream &operator <<(ostream, instructor );
void setSalary(int);
void getNumOfChildren(int);
void setMarialStatus(string);
};
#endif
instructor.cpp
#include <iostream>
#include <string>
#include "instructor.h"
using namespace std;
instructor::instructor() {
}
instructor::instructor(string a , string b, string c , int chil , int sal ,string mar):person(a,b,c)
{
children = chil;
salary = sal;
maritalStatus = mar;
}
instructor instructor::operator ++()
{
children=children+1;
return *this;
}
int instructor::calcSalary() {
int new_sal;
new_sal = salary + children*0.1;
return new_sal;
}
int instructor::getSalary() {
cout <<"Here is the result of your query:"<<endl;
cout <<"================================="<<endl;
cout<< "Salary: "<<salary<<""<<endl;
cout <<"================================="<<endl;
cout <<endl;
return salary;
}
int instructor::getNumOfChildren() {
cout <<"Here is the result of your query:"<<endl;
cout <<"================================="<<endl;
cout<< "Number of children: "<<children<<""<<endl;
cout <<"================================="<<endl;
cout <<endl;
return children;
}
string instructor::getMarialStatus() {
cout <<"Here is the result of your query:"<<endl;
cout <<"================================="<<endl;
cout<< "Marital Status: "<<maritalStatus<<""<<endl;
cout <<"================================="<<endl;
cout <<endl;
return maritalStatus;
}
friend ostream& operator<<(ostream& os, instructor& v){
os << v.children;
return os;
}
void instructor::setSalary(int sal) {
salary = sal;
}
void instructor::getNumOfChildren(int nmc) {
children = nmc;
}
void instructor::setMarialStatus(string sms) {
maritalStatus = sms;
}
void instructor::print() {
person::print();
cout <<"Here is the result of your query:"<<endl;
cout <<"================================="<<endl;
cout<< "Marital Status: "<<maritalStatus<<""<<endl;
cout<< "Number of children: "<<children<<""<<endl;
cout<< "Salary: "<<salary<<""<<endl;
cout <<"================================="<<endl;
cout <<endl;
}
I am getting the following errors:
instructor.cpp(75) : error C2255: 'friend' : not allowed outside of a class definition
instructor.cpp(76) : error C2248: 'instructor::children' : cannot
access private member declared in class 'instructor' 1>
c:\documents and settings\george\my documents\visual studio
2005\projects\hana\hana\instructor.h(7) : see declaration of
'instructor::children' 1>
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========
I am using visual studio 2005. Why am I getting those errors?
All of this is cause by my attempt in overloading the operator cout:
friend ostream& operator<<(ostream& os, instructor& v){
os << v.children;
return os;
}
Why is not working?

Answer 1

There are two problems. The first is that you can't use friend outside a class, as the error says. But you don't need to; having declared the function as a friend within the class you just define it outside without having to mention the friend-ness again.
But the other problem is that your declaration and definition don't match. You declared this as a friend:
ostream &operator <<(ostream, instructor );
And then you defined this:
ostream& operator<<(ostream&, instructor&)
Those aren't the same, but they need to be.