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vect.h
// vect.h -- Vector class with <<, mode state
// vect.h -- Vector class with <<, mode state
#ifndef VECTOR_H_
#define VECTOR_H_
#include <iostream>
namespace VECTOR
{
class Vector
{
public:
enum Mode {RECT, POL};
// RECT for rectangular, POL for Polar modes
private:
double x; // horizontal value
double y; // vertical value
// Newly added:remove mag and ang
// double mag; // length of vector
// double ang; // direction of vector in degrees
Mode mode; // RECT or POL
// private methods for setting values
// Newly added: as we use magval() and angval(), and don't store mag and ang
// therefor no need to keep these 2 data components
// void set_mag();
// void set_ang();
void set_x(double mag, double ang);
void set_y(double mag, double ang);
public:
Vector();
Vector(double n1, double n2, Mode form = RECT);
void reset(double n1, double n2, Mode form = RECT);
~Vector();
double xval() const
{
return x; // report x value
}
double yval() const
{
return y; // report y value
}
// Newly added: replace mag with its expression
double magval() const
{
return sqrt(x * x + y * y); // report magnitude
}
double angval() const
{
if (x == 0.0 && y == 0.0)
return 0.0;
else
return atan2(y, x);
}// report angle
void polar_mode(); // set mode to POL
void rect_mode(); // set mode to RECT
// operator overloading
Vector operator+(const Vector & b) const;
Vector operator-(const Vector & b) const;
Vector operator-() const;
Vector operator*(double n) const;
// friends
friend Vector operator*(double n, const Vector & a);
friend std::ostream & operator<<(std::ostream & os, const Vector & v);
};
} // end namespace VECTOR
#endif
vect.cpp
// vect.cpp -- methods for the Vector class
#include <cmath>
#include "vect.h" // includes <iostream>
using std::sqrt;
using std::sin;
using std::cos;
using std::atan;
using std::atan2;
using std::cout;
namespace VECTOR
{
// compute degrees in one radian
const double Rad_to_deg = 45.0 / atan(1.0);
// should be about 57.2957795130823
// private methods
// set x from polar coordinate
// Newly added:alter,consider replace mag with magval(), ang with angval()
// but magval() needs x to to calculate,they can't help each other
void Vector::set_x(double mag,double ang)
{
x = mag * cos(ang);
}
// set y from polar coordinate
// Newly added:alter,replay mag with magval(), ang with angval()
void Vector::set_y(double mag, double ang)
{
y = mag * sin(ang);
}
// public methods
// Newly added: remove mag and ang
Vector::Vector() // default constructor
{
x = y = 0.0;
mode = RECT;
}
// construct vector from rectangular coordinates if form is r
// (the default) or else from polar coordinates if form is p
Vector::Vector(double n1, double n2, Mode form)
{
mode = form;
if (form == RECT)
{
x = n1;
y = n2;
// Newly added:remove these 2 methods
// set_mag();
// set_ang();
}
else if (form == POL)
{
// Newly added:remove these 2 variable
// mag = n1;
// ang = n2 / Rad_to_deg;
// inside(),use n1,n2 as mag,ang
set_x(n1,n2);
set_y(n1,n2);
}
else
{
cout << "Incorrect 3rd argument to Vector() -- ";
cout << "vector set to 0\n";
// Newly added:remove these 2 variable
x = y = 0.0;
mode = RECT;
}
}
// reset vector from rectangular coordinates if form is
// RECT (the default) or else from polar coordinates if
// form is POL
void Vector:: reset(double n1, double n2, Mode form)
{
mode = form;
if (form == RECT)
{
x = n1;
y = n2;
// Newly added:remove these 2 methods
// set_mag();
// set_ang();
}
else if (form == POL)
{
// Newly added:remove these 2 variable
// mag = n1;
// ang = n2 / Rad_to_deg;
set_x(n1, n2);
set_y(n1, n2);
}
else
{
cout << "Incorrect 3rd argument to Vector() -- ";
cout << "vector set to 0\n";
// Newly added:remove these 2 variable
x = y = 0.0;
mode = RECT;
}
}
Vector::~Vector() // destructor
{
}
void Vector::polar_mode() // set to polar mode
{
mode = POL;
}
void Vector::rect_mode() // set to rectangular mode
{
mode = RECT;
}
// operator overloading
// add two Vectors
Vector Vector::operator+(const Vector & b) const
{
return Vector(x + b.x, y + b.y);
}
// subtract Vector b from a
Vector Vector::operator-(const Vector & b) const
{
return Vector(x - b.x, y - b.y);
}
// reverse sign of Vector
Vector Vector::operator-() const
{
return Vector(-x, -y);
}
// multiply vector by n
Vector Vector::operator*(double n) const
{
return Vector(n * x, n * y);
}
// friend methods
// multiply n by Vector a
Vector operator*(double n, const Vector & a)
{
return a * n;
}
// display rectangular coordinates if mode is RECT,
// else display polar coordinates if mode is POL
std::ostream & operator<<(std::ostream & os, const Vector & v)
{
if (v.mode == Vector::RECT)
os << "(x,y) = (" << v.x << ", " << v.y << ")";
else if (v.mode == Vector::POL)
{
os << "(m,a) = (" << v.magval() << ", "
<< v.angval() * Rad_to_deg << ")";
}
else
os << "Vector object mode is invalid";
return os;
}
} // end namespace VECTOR
main
// randwalk.cpp -- using the Vector class
// compile with the vect.cpp file
#include <iostream>
#include <cstdlib> // rand(), srand() prototypes
#include <ctime> // time() prototype
#include "vect.h"
int main()
{
using namespace std;
using VECTOR::Vector;
srand(time(0)); // seed random-number generator
double direction;
Vector step;
Vector result(0.0, 0.0);
unsigned long steps = 0;
double target;
double dstep;
cout << "Enter target distance (q to quit): ";
while (cin >> target)
{
cout << "Enter step length: ";
if (!(cin >> dstep))
break;
while (result.magval() < target)
{
direction = rand() % 360;
step.reset(dstep, direction, Vector::POL);
result = result + step;
steps++;
}
cout << "After " << steps << " steps, the subject "
"has the following location:\n";
cout << result << endl;
result.polar_mode();
cout << " or\n" << result << endl;
cout << "Average outward distance per step = "
<< result.magval()/steps << endl;
steps = 0;
result.reset(0.0, 0.0);
cout << "Enter target distance (q to quit): ";
}
cout << "Bye!\n";
/* keep window open
cin.clear();
while (cin.get() != '\n')
continue;
cin.get();
*/
return 0;
}