【C++ Primer Plus习题】11.1

问题:

解答:
main.cpp

#include <iostream>
#include <fstream>
#include "Vector.h"
#include <time.h>
using namespace std;
using namespace VECTOR;int main()
{ofstream fout;fout.open("randwalk.txt");srand(time(0));double direction;Vector step;Vector result(0.0, 0.0);unsigned long steps = 0;double target;double dstep;cout << "请输入目标距离(q结束):";while (cin>>target&&cin.get()!='q'){cout << "请输入步长:";if (!(cin >> dstep))break;fout << "目标距离: " << target << ", 步长: " << dstep << endl;while (result.magval()<target){fout << steps << " : " << result << endl;direction = rand() % 360;step.reset(dstep, direction, Vector::POL);result =result+step;steps++;}cout << "经过 " << steps << "步,实验对象的位置如下:\n";cout << result << endl;fout << "经过 " << steps << "步,实验对象的位置如下:\n";fout << result << endl;result.polar_mode();cout << " 或者\n" << result << endl;cout << "每一步向外的平均距离 = " << result.magval() / steps << endl;fout << " 或者\n" << result << endl;fout << "每一步向外的平均距离 = " << result.magval() / steps << endl;steps = 0;result.reset(0.0, 0.0);cout << "请输入目标距离(q结束):";}cout << "Bye!\n";fout.close();return 0;
}

Vector.h

#pragma once
#include <iostream>
using namespace std;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 from = 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 ostream& operator<<(ostream& os, const Vector& v);};}

Vector.cpp

#include "Vector.h"
#include <cmath>namespace VECTOR
{const double Rad_to_deg = 45.0 / atan(1.0);//45/(π/4)void Vector::set_mag(){mag = sqrt(x * x + y * y);}void Vector::set_ang(){if (x == 0.0 && y == 0.0){ang = 0.0;}else{ang = atan2(y, x);}}void Vector::set_x(){x = mag * cos(ang);}void Vector::set_y(){y = mag * sin(ang);}Vector::Vector(){x = y = mag = ang = 0.0;mode = RECT;}Vector::Vector(double n1, double n2, Mode form){mode = form;if (mode == RECT){x = n1;y = n2;set_mag();set_ang();}else if (mode == POL){mag = n1;ang = n2 / Rad_to_deg;set_x();set_y();}else{cout << "错误!" << endl;x = y = mag = ang = 0.0;mode = RECT;}}void Vector::reset(double n1, double n2, Mode from){mode = from;if (mode == RECT){x = n1;y = n2;set_mag();set_ang();}else if (mode == POL){mag = n1;ang = n2 / Rad_to_deg;set_x();set_y();}else{cout << "错误!" << endl;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(x * n, y *n);}Vector operator*(double n, const Vector& a){return a * n;}ostream& operator<<(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 invalid";}return os;}}

运行结果:

考查点:

• 写文件
  
  

• 运算符重载
  

• 友元
  

• 命名空间
  

• 默认参数
  

• 内联函数
  

• 枚举
  

• 随机数
  
  

• 数学
  

2024年9月5日15:02:35