Question

I cannot get the C++ code below to compile correctly. Any assistance would be greatly appreciated!

***main.cpp driver file***

#include
#include
#include "vector.h"
using namespace std;

int main()
{
    vectorInfo v1(3, -1);
    vectorInfo v2(2, 3);

    cout << "v1 : ";
    v1.print();

    cout << "v2 : ";
    v2.print();

    cout << "v1 magnitude : " << v1.magnitude() << endl;

    cout << "v1 direction : " << v1.direction() << " radians" << endl;

    cout << "v1 + v2 : ";
    (v1 + v2).print();

    cout << "v1 - v2 : ";
    (v1 - v2).print();

    cout << "v1 * v2 : " << v1 * v2 << endl;

    cout << "v1 == v2 : " << (v1 == v2) << endl;
}

***vector.cpp implementation file***

#include "vector.h"
#include
#include
using namespace std;

vectorInfo::vectorInfo()
{
    x = 0;
    y = 0;
}

vectorInfo::vectorInfo(double a, double b)
{
    x = a;
    y = b;
}

void vectorInfo::set(double a, double b)
{
    x = a;
    y = b;
}

double vectorInfo::magnitude()
{
    return sqrt(x * x + y * y);
}

double vectorInfo::direction()
{
    return atan(y / x);
  
}

void vectorInfo::print()
{
    cout << x << " " << y << endl;
}

vectorInfo vectorInfo::operator-(vectorInfo const& b)
{
    return vectorInfo(x - b.x, y - b.y);
}

double vectorInfo::operator*(vectorInfo const& b)
{
    return x * b.x + y * b.y;
}

const vectorInfo operator+(vectorInfo const& a, vectorInfo const& b)
{
    return vectorInfo(a.x + b.x, a.y + b.y);
}

bool operator==(vectorInfo const& a, vectorInfo const& b)
{
    return a.x == b.x && a.y == b.y;
}

***vector.h header file:***

#ifndef VECTOR_H
#define VECTOR_H

class vectorInfo
{
    public:
        vectorInfo();

        vectorInfo(double a, double b);

        // member functions

        void set(double a, double b);

        double magnitude();

        double direction();

        void print();

        // member operators

        vectorInfo operator-(vectorInfo const& b);

        double operator*(vectorInfo const& b);

    private:
        double x;

        double y;
};

        // non member operators
        const vectorInfo operator+(vectorInfo const& a, vectorInfo const& b);

        bool operator==(vectorInfo const& a, vectorInfo const& b);

#endif /* VECTOR_H */

Answer 1

changes done are friend make private member accessible even when this is non-member functions

   friend   const vectorInfo operator+(vectorInfo const& a, vectorInfo const& b);
friend bool operator==(vectorInfo const& a, vectorInfo const& b);

and void print() const; // declare it const

/* vector.h */

#ifndef VECTOR_H
#define VECTOR_H
class vectorInfo
{
public:
vectorInfo();
vectorInfo(double a, double b);
// member functions
void set(double a, double b);
double magnitude();
double direction();
void print() const; // declare it const
// member operators
vectorInfo operator-(vectorInfo const& b);
double operator*(vectorInfo const& b);
private:
double x;

double y;
   // non member operators but friend to access private members  
   friend   const vectorInfo operator+(vectorInfo const& a, vectorInfo const& b);
friend bool operator==(vectorInfo const& a, vectorInfo const& b);

};
      
#endif /* VECTOR_H */

/* vector.cpp */

#include "vector.h"
#include<iostream>
#include<math.h>
using namespace std;

vectorInfo::vectorInfo()
{
x = 0;
y = 0;
}

vectorInfo::vectorInfo(double a, double b)
{
x = a;
y = b;
}

void vectorInfo::set(double a, double b)
{
x = a;
y = b;
}

double vectorInfo::magnitude()
{
return sqrt(x * x + y * y);
}

double vectorInfo::direction()
{
return atan(y / x);
  
}

void vectorInfo::print() const
{
cout << x << " " << y << endl;
}

vectorInfo vectorInfo::operator-(vectorInfo const& b)
{
return vectorInfo(x - b.x, y - b.y);
}

double vectorInfo::operator*(vectorInfo const& b)
{
return x * b.x + y * b.y;
}

const vectorInfo operator+(vectorInfo const& a, vectorInfo const& b)
{
return vectorInfo(a.x + b.x, a.y + b.y);
}

bool operator==(vectorInfo const& a, vectorInfo const& b)
{
return a.x == b.x && a.y == b.y;
}

/* main.cpp */

#include "vector.h"
#include<iostream>
using namespace std;
int main()
{
vectorInfo v1(3, -1);
vectorInfo v2(2, 3);
cout << "v1 : ";
v1.print();
cout << "v2 : ";
v2.print();
cout << "v1 magnitude : " << v1.magnitude() << endl;
cout << "v1 direction : " << v1.direction() << " radians" << endl;
cout << "v1 + v2 : ";
(v1 + v2).print();
cout << "v1 - v2 : ";
(v1 - v2).print();
cout << "v1 * v2 : " << v1 * v2 << endl;
cout << "v1 == v2 : " << (v1 == v2) << endl;
}

/* OUTPUT */