Some School stuff (11)

//Class and stuff

// Class Drill for Drill Object
#include <iostream>

using namespace std;

const double PI = 3.142;

class Drill {

public:
    Drill () {}
    Drill (double,double,double);
    double mrr() const;
    double torque (double) const;

private:
    double diameter,
           feed,
           speed;

friend istream& operator >> (istream&, Drill&);
friend ostream& operator << (ostream&, const Drill&);
};

//
// Constructor 2: Initializes all components
//
Drill::Drill(double drillDiam, double drillFeed, double drillSpeed)
{
    diameter = drillDiam;
    feed = drillFeed;
    speed = drillSpeed;
}

//
// material removal rate: mm^3/sec
//
double Drill :: mrr() const
{
    return (PI*0.25*diameter*diameter*feed*speed/60.0);
}

//
// torque (W.s) on drill based on unit power (W.s/mm^3)
// dissipated
// in cutting workpiece material
//
double Drill :: torque (double unitPower) const
{
    double radSec; // rotational speed in radians per second

    radSec = speed*2*PI/60.0;
    return (unitPower*mrr()/radSec);
}
//
// Extract from input source the three components of a Drill object
//
istream& operator >> (istream& is, Drill& dr)
{
    is >> dr.diameter >> dr.feed >> dr.speed;
    return is;
}

//
// Display a drill object, labeling all components
//
ostream& operator << (ostream& os, const Drill& dr)
{
    os << "Drill " << endl << " diameter: " << dr.diameter << " mm" <<endl
        <<" feed: " << dr.feed << "  mm/rev" << endl << "    speed: " << dr.speed << "   rpm" << endl;
        return os;
}

//
// Driver to declare and manipulate a drill object
//
int main ()
{
    Drill drillA;
    double unitPower;

    cout << "Describe a drill by entering diameter (mm), feed (mm/rev). "
        << "speed (rpm) " << endl << "=>";
    cin >> drillA;
    cout << "Enter average power unit for workpiece material (W.s/mm^3)"
        <<endl << "=>";
        cin>>unitPower;

        cout << endl << drillA << endl;
        cout << "Drill's material removal rate is: " <<
    drillA.mrr() <<
                " mm^3/sec" << endl;
        cout << "Torque on the drill when drilling the given workpiece material: "
             << drillA.torque(unitPower) << "W.s" << endl;
        return 0;
}