vector.h

  1. #ifndef PRO1_VECTOR_H
  2. #define PRO1_VECTOR_H
  4. #include <iostream>
  6. using namespace std;
  8. namespace VECTOR{
  10.     class Vector {
  11.     private:
  12.         double x;
  13.         double y;
  14.         double mag;
  15.         double ang;
  16.         char mode;
  18.         // private methods for setting values
  19.         void set_mag();
  20.         void set_ang();
  21.         void set_x();
  22.         void set_y();
  24.     public:
  25.         Vector();
  26.         Vector(double n1, double n2, char form = 'r');
  27.         ~Vector();
  28.         void set(double n1, double n2, char form = 'r');
  29.         double xval()const { return x;}
  30.         double yval()const { return y;}
  31.         double magval()const { return mag;}
  32.         double angval()const { return ang;}
  33.         void polar_mode();
  34.         void rect_mode();
  35.         // operator overloading
  36.         Vector operator+(const Vector & b)const ;
  37.         Vector operator-(const Vector & b)const ;
  38.         Vector operator-()const ;
  39.         Vector operator*(double n)const ;
  40.         // friends
  41.         friend Vector operator*(double n, const Vector & a);
  42.         friend ostream &operator << (ostream & os, const Vector & vector);
  43.     };
  44. }
  46. #endif //PRO1_VECTOR_H

vector.cpp

  1. #include "vector.h"
  2. #include <cmath>
  4. using std::sin;
  5. using std::cos;
  6. using std::atan2;
  7. using std::cout;
  8. using std::ostream;
  10. namespace VECTOR{
  12.     const double Rad_to_deg = 57.2957795130823;
  13.     // private methods
  14.     // calculates magnitude from x and y
  15.     void Vector::set_mag() {mag - sqrt(x * x + y * y);}
  16.     void Vector::set_ang() {
  17.         if(x == 0.0 && y == 0.0){
  18.             ang = 0.0;
  19.         } else {
  20.             ang = atan2(y, x);
  21.         }
  22.     }
  23.     void Vector::set_x() {x = mag * cos(ang);}
  24.     void Vector::set_y() {y = mag * sin(ang);}
  26.     Vector::Vector() {
  27.         x = y = mag = ang = 0.0;
  28.         mode = 'r';
  29.     }
  31.     Vector::Vector(double n1, double n2, char form) {
  32.         mode = form;
  33.         if (form == 'r') {
  34.             x = n1;
  35.             y = n2;
  36.             set_mag();
  37.             set_ang();
  38.         } else if (form == 'p'){
  39.             mag = n1;
  40.             ang = n2 / Rad_to_deg;
  41.             set_x();
  42.             set_y();
  43.         } else{
  44.             cout << "Incorrect 3rd argument to Vector()-- ";
  45.             cout << "vector set to 0\n";
  46.             x = y = mag = ang = 0.0;
  47.             mode = 'r';
  48.         }
  49.     }
  51.     void Vector::set(double n1, double n2, char form) {
  52.         mode = form;
  53.         if (form == 'r') {
  54.             x = n1;
  55.             y = n2;
  56.             set_mag();
  57.             set_ang();
  58.         } else if (form == 'p'){
  59.             mag = n1;
  60.             ang = n2 / Rad_to_deg;
  61.             set_x();
  62.             set_y();
  63.         } else{
  64.             cout << "Incorrect 3rd argument to Vector()-- ";
  65.             cout << "vector set to 0\n";
  66.             x = y = mag = ang = 0.0;
  67.             mode = 'r';
  68.         }
  69.     }
  71.     Vector::~Vector() {}
  73.     void Vector::polar_mode() {mode = 'p';}
  75.     void Vector::rect_mode() {mode = 'r';}
  77.     Vector Vector::operator+(const VECTOR::Vector &b) const { return Vector(x + b.x, y + b.y); }
  78.     Vector Vector::operator-(const VECTOR::Vector &b) const { return Vector(x - b.x, y - b.y); }
  79.     Vector Vector::operator-() const { return Vector(-x, -y); }
  80.     Vector Vector::operator*(double n) const { return Vector(n * x, n * y); }
  81.     Vector operator *(double n, const Vector & a){ return a * n; }
  83.     ostream & operator<< (ostream & os, const Vector & vector){
  84.         if (vector.mode == 'r') {
  85.             os << "(x,y) = " << vector.x << ", " << vector.y ;
  86.         } else if (vector.mode == 'p') {
  87.             os << "(m, a) = " << vector.mag << ", " << vector.ang * Rad_to_deg ;
  88.         } else
  89.             os << "Vector object mode is invalid";
  90.         return os;
  91.     }
  92. }

使用Vector类模拟随机行走

  1. #include <iostream>
  2. #include <cstdlib>
  3. #include "module4/vector.h"
  5. using namespace std;
  7. // 使用Vector类模拟随机行走
  8. void randwalk(){
  9.     using VECTOR::Vector;
  10.     srand(time(0));
  11.     double direction;
  12.     Vector step;
  13.     Vector result(0.0, 0.0);
  14.     unsigned long steps = 0;
  15.     double dstep;
  16.     double target;
  17.     cout << "Enter target distance(q to quit): ";
  18.     while (cin >> target) {
  19.         cout << "Enter step length: ";
  20.         if (!(cin >> dstep)) {
  21.             break;
  22.         }
  23.         while (result.magval() < target){
  24.             direction = rand()%360;
  25.             step.set(dstep, direction, 'p');
  26.             result = result + step;
  27.             steps++;
  28.         }
  29.         cout << "After " << steps << " steps, the subject has the following location: \n";
  30.         cout << result << endl;
  31.         result.polar_mode();
  32.         cout << " or\n" << result << endl;
  33.         cout << "Average outward distance per step = " << result.magval()/steps << endl;
  34.         steps = 0;
  35.         result.set(0.0, 0.0);
  36.         cout << "Enter target distance (q to quit): ";
  37.     }
  38.     cout << "Bye!\n";
  39. }
  41. int main() {
  42.     randwalk();
  43.     return 0;
  44. }