Help with subscripting operator overload?

//What the operator[] should do:
//operator[]

//The indexing operator should be overloaded to provide accessor methods for the class. Subscript 0 should //provide access to the x component value of the vector; subscript 1 to the y component and subscript 2 to //the z component. Subscript values other than 0, 1, or 2 produce undefined results. For speed, no error //checking needs to be done.

//The choice of how the data members are implemented in the class could greatly affect the complexity of //overloading this particular operator.

//Don't forget that this operator needs to be overloaded twice, once for getting a value and once for //setting a value.


//beginning of Vector3.h file
#ifndef VECTOR_H
#define VECTOR_H

#include <iostream>

using namespace std;

class Vector3
        {
        friend ostream & operator<<(ostream &, const Vector3 &);
        friend Vector3 operator*(float, const Vector3 &);

        float coord[3];                         //Do I even need this for subscript?

        private:

                float x;
                float y;
                float z;

        public:

                Vector3();
                Vector3(float, float, float);
                Vector3 operator+(const Vector3 &) const;
                Vector3 operator-(const Vector3 &) const;
                float operator*(const Vector3 &) const;
                Vector3 operator*(float rightOp) const;
                float operator[](int index) const;                       //Read subscript operator
                float & operator [] (int index);            //Write subscript operator
                bool operator==(const Vector3 &) const;
        };

#endif
//end of Vector3.h File!

-----------------------------------------------------------------------

//start of Vector3.cpp file


#include <iostream>
#include <iomanip>
#include "Vector3.h"

using namespace std;

Vector3::Vector3()
        {
                x = 0;
                y = 0;
                z = 0;
        }

Vector3::Vector3( float newX, float newY, float newZ)
        {
                x = newX;
                y = newY;
                z = newZ;
        }

ostream & operator<<(ostream & osObject, const Vector3 & rightOp)
        {
        osObject << "(" << rightOp.x << ", " << rightOp.y << ", " << rightOp.z << ")";

        return osObject;
        }

Vector3 Vector3::operator+(const Vector3 & rightOp) const
        {
                Vector3 result = *this;

                result.x += rightOp.x;
                result.y += rightOp.y;
                result.z += rightOp.z;

        return result;
        }

Vector3 Vector3::operator-(const Vector3 & rightOp) const
        {
                Vector3 result = *this;

                result.x -= rightOp.x;
                result.y -= rightOp.y;
                result.z -= rightOp.z;
        return result;
        }

float Vector3::operator*(const Vector3 & rightOp) const
        {
                float result = (x * rightOp.x) + (y * rightOp.y) + (z * rightOp.z);

                return result;
        }

Vector3 Vector3::operator*(float rightOp) const
        {
                Vector3 result = *this;

                result.x *= rightOp;
                result.y *= rightOp;
                result.z *= rightOp;

        return result;
        }

Vector3 operator*(float leftOp, const Vector3 & rightOp)
        {
                Vector3 result = rightOp;

                result.x *= leftOp;
                result.y *= leftOp;
                result.z *= leftOp;

        return result;
        }

bool Vector3::operator==(const Vector3 & rightOp) const
        {
        return (x == rightOp.x && y == rightOp.y && z == rightOp.z);
        }


float Vector3::operator [] (int index) const                         //This is to read subscript
        {
        return coord[index];
        }


float & Vector3::operator [] (int index)            //this is to write to subscript
        {
        return coord[index];
        }

//end of Vector3.cpp file!

----------------------------------------------------------------------------------
//File to test the coding

#include <iostream>
#include "Vector3.h"

using std::cout;
using std::endl;

int main()
        {
        int test = 1;

        cout << "\nTest " << test++ << ": Constructor and printing\n" << endl;

        const Vector3 v1, v2(1.0, 2.0, 3.0);

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

        cout << "\nTest " << test++ << ": Addition and subtraction\n" << endl;

        const Vector3 v3(1.0, 2.0, 3.0), v4(-2.0, 3.0, -1.0);

        cout << "v3: " << v3 << endl;
        cout << "v4: " << v4 << endl << endl;

        cout << "v3 + v4 is " << v3 + v4 << endl;
        cout << "v3 - v3 is " << v3 - v4 << endl;

        cout << "\nTest " << test++ << ": Vector multiplication\n" << endl;

        cout << "The scalar product of " << v3 << " and " << v4 << " is ";
        cout << v3 * v4 << endl;

        cout << "\nTest " << test++ << ": Scalar multiplication\n" << endl;

        float k = 2.345;

        cout << v3 << " * " << k << " = " << v3 * k << endl;
        cout << k << " * " << v4 << " = " << k * v4 << endl;

        cout << "\nTest " << test++ << ": Subscripting\n" << endl;              //TEST I HAVE PROBLEMS WITH

        const Vector3 v5(3.2, -5.4, 5.6);
        Vector3 v6(1.3, 2.4, -3.1);

        cout << "v5: " << v5 << endl;
        cout << "v6: " << v6 << endl;

        cout << "v5[0] = " << v5[0] << endl;
        cout << "v5[1] = " << v5[1] << endl;
        cout << "v5[2] = " << v5[2] << endl;

        v6[0] = -2.4;
        v6[1] = -1.3;
        v6[2] = 17.5;

        cout << "v6: " << v6 << endl;
        v6 = v5;
        cout << "v6: " << v6 << endl;

        cout << "\nTest " << test++ << ": Equality\n" << endl;

        const Vector3 v7(-1, 2, -1), v8(-1, 2, -2);

        cout << v7 << " and " << v7 << " are ";

        if (v7 == v7)
                cout << "equal" << endl;
        else
                cout << "not equal" << endl;

        cout << v7 << " and " << v8 << " are ";

        if (v7==v8)
                cout << "equal" << endl;
        else
                cout << "not equal" << endl;

        return 0;
        }