c++primer plus 清单11.13 ，11.14 , 11.15

首先清单11.13
#ifndef VECTOR_H_
#define VECTOR_H_
#include
namespace VECTOR
{
class Vector
{
public:
enum Mode { RECT, POL };
private:
double x;
double y;
double mag;
double ang;
Mode mode;
void set_mag();
void set_ang();
void set_x();
void set_y();
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; }
double yval()const { return y; }
double magval() const { return mag; }
double angval()const { return ang; }
void polar_mode();
void rect_mode();
Vector operator +(const Vector&b)const;
Vector operator -(const Vector&b)const;
Vector operator -()const;
Vector operator*(double n)const;
friend Vector operator*(double n,const Vector &a);
friend std::ostream&operator<<(std::ostream &os, const Vector &v);
};
}

#endif

然后 11.14
#include “stdafx.h”
#include
#include"vector.h"
using std::sqrt;
using std::sin;
using std::cos;
using std::atan;
using std::atan2;
using std::cout;

namespace VECTOR
{
const double Rad_to_deg = 45.0 / atan(1.0);
void Vector::set_mag()
{
mag = sqrt(xx + yy);
}
void Vector::set_ang()
{
if (x == 0.0&&y == 0.0)
ang = 0.0;
else ang = atan2(y, x);
}
void Vector::set_x()
{
x = magcos(ang);
}
void Vector::set_y()
{
y = magsin(ang);
}
Vector::Vector()
{
x = y = mag = ang = 0.0;
mode = RECT;
}
Vector::Vector(double n1, double n2, Mode form)
{
mode = form;
if (form == RECT)
{
x = n1;
y = n2;
set_mag();
set_ang();
}
else if (form == POL)
{
mag = n1;
ang = n2 / Rad_to_deg;
set_x();
set_y();
}
else
{
cout << “Incorrect 3rd argument to Vector”;
cout << “Vector set to 0\n”;
x = y = mag = ang = 0.0;
mode = RECT;

	}
}
void Vector::reset(double n1, double n2, Mode form)
{
	mode = form;
	if (form == RECT)
	{
		x = n1;
		y = n2;
		set_mag();
		set_ang();
	}
	else if (form == POL)
	{
		mag = n1;
		ang = n2 / Rad_to_deg;
		set_x();
		set_y();
	}
	else
	{
		cout << "Incorrect 3rd argument to Vector";
		cout << "Vector set to 0\n";
		x = y = mag = ang = 0.0;
		mode = RECT;
	}
}

Vector::~Vector()
{
}
void Vector::polar_mode()
{
	mode = POL;
}
void Vector::rect_mode()
{
	mode = RECT;
}
Vector Vector::operator+(const Vector & b) const
{
	return Vector (x+b.x,y+b.y);
}

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

Vector Vector::operator-() const
{
	return Vector(-x , -y);
}

Vector Vector::operator*(double n) const
{
	return Vector(n*x,n*y);
}


Vector operator*(double n, const Vector & a)
{
	return Vector(a*n);
}

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.mag << ","
			<< v.ang*Rad_to_deg << ")";
	}
	else
		os << "Vector object mode is invailed";
	return os;

}

}
最后是11.15
// 11月21.cpp: 定义控制台应用程序的入口点。
//

#include “stdafx.h”
#include
#include
#include
#include"vector.h"

int main()
{
using namespace std;
using VECTOR::Vector;
srand(time(0));
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 distant per step =”
<< result.magval() / steps << endl;
steps = 0;
result.reset(0.0, 0.0);
cout << "Enter target distant (q to quit): ";
}cout << “bye!\n”;
cin.clear();
while (cin.get() != ‘\n’)
continue;
return 0;
}