Tutorial7 Q4 [Top level method]

// http://pastebin.com/u/TheWhiteFang
// Tutorial7 Q4 [Top level method]
#include <iostream>
#include <math.h>
using namespace std;
#define PI 3.141

class CCylinder{
    float m_Radius;
    float m_Height;
    float m_SurfaceArea;

public:
    CCylinder (float inRadius = 0.0 , float inHeight = 0.0){

        m_Radius = inRadius;
        m_Height = inHeight;
        m_SurfaceArea = ( 2 * PI * inRadius*inRadius) + (2 * PI * inRadius * inHeight);

    }
friend CCylinder operator+ (const CCylinder &inVal1, const CCylinder &inVal2);
friend ostream &operator<<(ostream &output, const CCylinder &source);
};

//top level function

CCylinder operator+ (const CCylinder &inVal1, const CCylinder &inVal2)
{
    CCylinder temp;

    temp.m_SurfaceArea = (PI*inVal2.m_Radius*inVal2.m_Radius)-(PI*inVal1.m_Radius*inVal1.m_Radius);
    temp.m_SurfaceArea += (PI*inVal2.m_Radius*inVal2.m_Radius) + (PI*inVal1.m_Radius*inVal1.m_Radius);
    temp.m_SurfaceArea += (2*PI*inVal1.m_Radius*inVal1.m_Height)+(2*PI*inVal2.m_Radius*inVal2.m_Height);


    return temp;

}

//ostream operator
ostream &operator<<(ostream &output, const CCylinder &source){
    output << "Surface Area = "<< source.m_SurfaceArea << " cm2 )" << endl;
    return output;
}


int main()
{
    CCylinder cyObj1((float)2.5, (float)3.5);
    CCylinder cyObj2((float)3.5, (float)4.5);
    cout<< "Cylinder 1 (" << cyObj1 << /*")" <<*/ endl;
    cout<< "Cylinder 2 (" << cyObj2 <</* ")" <<*/ endl;

    CCylinder cyObj3 = cyObj1 + cyObj2;
    cout << "Cylinder 1 + Cylinder 2 = ";
    cout << "(" << cyObj3 <</* ")" <<*/ endl;
    return 0;
}