1.修改程序清单11.15，使之将一系列连续的随机漫步者位置写入到文件中。对于每个位置，用步号进行标示。另外，让该程序将初始条件（目标距离和步长）以及结果小结写入到该文件中。
#include <iostream>
#include <cstdlib>
#include <ctime>
#include <fstream>
#include "vector.h"
using namespace std;
using VECTOR::Vector;
int main() {
ofstream outFile;
outFile.open("exercise1.txt");
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;
outFile << "Target Distance: " << target << ", Step Size: " << dstep << endl;
while (result.magval() < target)
{
direction = rand() % 360;
step.set(dstep, direction, 'p');
result = result + step;
outFile << steps << ": (x,y) = " << "(" << step.xval() << ", " << step.yval() << ")" << endl;
steps++;
}
outFile << "After " << steps << " steps, the subject "
"has the following location:\n";
outFile << "(x,y)=" << result << endl;
result.polar_mode();
outFile << " or\n" << result << endl;
outFile << "Average outward distance per step = "
<< result.magval() / steps << endl;
outFile << "===================================================="<<endl;
outFile << "COPYRIGHT 2018 WWW.YUSHUAI.XYZ" << endl;
steps = 0;
result.set(0.0, 0.0);
cout << "Enter target distance (q to quit): ";
}
outFile.close();
cout << "Bye~" << endl;
system("pause");
return 0;
}
2.对Vector类的头文件（程序清单11.13）和实现文件（程序清单11.14）进行修改，使其不再存储矢量的长度和角度，而是在magval()和angval()被调用时计算它们。
应保留公有接口不变（公有方法及其参数不变），但对私有部分（包括一些私有方法）和方法实现进行修改。然后，使用程序清单11.15对修改后的版本进行测试，结果应该与以前相同，因为Vector类的公有接口与原来相同。
vector.h
// vect.h -- Vector class with <<, mode state
#ifndef VECTOR_H_
#define VECTOR_H_
#include <iostream>
namespace VECTOR
{
class Vector
{
private:
double x; // horizontal value
double y; // vertical value
char mode; // 'r' = rectangular, 'p' = polar
// private methods for setting values
void set_x(double mag, double ang);
void set_y(double mag, double ang);
public:
Vector();
Vector(double n1, double n2, char form = 'r');
void set(double n1, double n2, char form = 'r');
~Vector();
double xval() const { return x; } // report x value
double yval() const { return y; } // report y value
double magval() const { return sqrt(x * x + y * y); } // report magnitude
double angval() const// report angle
{
if (x == 0.0 && y == 0.0)
return 0.0;
else
return atan2(y, x);
}
void polar_mode(); // set mode to 'p'
void rect_mode(); // set mode to 'r'
// 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
#pragma once
vector.cpp
#include <cmath>
#include "vector.h" // includes <iostream>
using std::sqrt;
using std::sin;
using std::cos;
using std::atan2;
using std::cout;
namespace VECTOR
{
const double Rad_to_deg = 57.2957795130823;
// private methods
// calculates magnitude from x and y
// set x from polar coordinate
void Vector::set_x(double mag, double ang)
{
x = mag * cos(ang);
}
// set y from polar coordinate
void Vector::set_y(double mag, double ang)
{
y = mag * sin(ang);
}
// public methods
Vector::Vector() // default constructor
{
x = y = 0.0;
mode = 'r';
}
// 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, char form)
{
mode = form;
if (form == 'r')
{
x = n1;
y = n2;
}
else if (form == 'p')
{
set_x(n1, n2);
set_y(n1, n2);
}
else
{
cout << "Incorrect 3rd argument to Vector() -- ";
cout << "vector set to 0\n";
x = y = 0.0;
mode = 'r';
}
}
// set vector from rectangular coordinates if form is r (the
// default) or else from polar coordinates if form is p
void Vector::set(double n1, double n2, char form)
{
mode = form;
if (form == 'r')
{
x = n1;
y = n2;
}
else if (form == 'p')
{
set_x(n1, n2);
set_y(n1, n2);
}
else
{
cout << "Incorrect 3rd argument to Vector() -- ";
cout << "vector set to 0\n";
x = y = 0.0;
mode = 'r';
}
}
Vector::~Vector() // destructor
{
}
void Vector::polar_mode() // set to polar mode
{
mode = 'p';
}
void Vector::rect_mode() // set to rectangular mode
{
mode = 'r';
}
// 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);
}
// multiple 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 r,
// else display polar coordinates if mode is p
std::ostream & operator<<(std::ostream & os, const Vector & v)
{
if (v.mode == 'r')
os << "(x,y) = (" << v.x << ", " << v.y << ")";
else if (v.mode == 'p')
{
os << "(m,a) = (" << v.magval() << ", "
<< v.angval() * Rad_to_deg << ")";
}
else
os << "Vector object mode is invalid";
return os;
}
} // end namespace VECTOR
3.修改程序清单11.15，使之报告N次测试中的最高、最低和平均步数（其中N是用户输入的整数），而不是报告每次测试的结果。
#include<iostream>
#include<cstdlib>
#include<ctime>
#include "vector.h"
using namespace std;
using VECTOR::Vector;
int main() {
srand(time(0));
double direction;
Vector step;
Vector result(0.0, 0.0);
unsigned long steps = 0;
double target;
double dstep;
unsigned long max = 0;
unsigned long min = 999;
double avg = 0;
int N;
cout << "请输入测试的次数：N=";
cin >> N;
cout << "第一次：" << endl;
int i;
for (i = 0; i < N; i++)
{
cout << "Enter target distance(ONLY ENTER NUMBER): ";
cin >> target;
cout << "Enter step length: ";
if (!(cin >> dstep))
break;
while (result.magval() < target)
{
direction = rand() % 360;
step.set(dstep, direction, 'p');
result = result + step;
steps++;
}
if (max < steps)
max = steps;
if (min > steps)
min = steps;
avg += steps;
result.polar_mode();
steps = 0;
result.set(0.0, 0.0);
}
avg /= N;
cout << "max: " << max << endl << "min: " << min << endl << "average: " << avg << endl;
cout << "Bye~";
system("pause");
return 0;
}
4.重新编写最后的Time类示例（程序清单11.10、程序清单11.11和程序清单11.12），使用友元函数来实现所有的重载运算符。
mytime3.h
#pragma once
#ifndef MYTIME3_H_
#define MYTIME3_H_
#include<iostream>
using namespace std;
class Time {
private:
int hours;
int minutes;
public:
Time();
Time(int h, int m = 0);
void AddMin(int m);
void AddHr(int h);
void Reset(int h = 0, int m = 0);
friend Time operator+(const Time & t1, const Time & t2);
friend Time operator-(const Time & t1, const Time & t2);
friend Time operator*(const Time &t, double n);
friend Time operator*(double m, const Time & t) { return t*m; }
friend ostream & operator<<(ostream & os, const Time & t);
};
#endif // !MYTIME_H_
mytime3.cpp
#include<iostream>
#include "mytime3.h"
using namespace std;
Time::Time() {
hours = minutes = 0;
}
Time::Time(int h, int m) {
hours = h;
minutes = m;
}
void Time::AddMin(int m) {
minutes += m;
hours += minutes / 0;
minutes %= 60;
}
void Time::AddHr(int h) {
hours += h;
}
void Time::Reset(int h, int m) {
hours = h;
minutes = m;
}
Time operator+(const Time & t1, const Time & t2) {
Time sum;
sum.minutes = t1.minutes + t2.minutes;
sum.hours = t1.hours + t2.hours + sum.minutes / 60;
sum.minutes %= 60;
return sum;
}
Time operator-(const Time & t1, const Time & t2) {
Time diff;
int tot1, tot2;
tot1 = t2.minutes + 60 * t2.hours;
tot2 = t1.minutes + 60 * t1.hours;
diff.minutes = (tot2 - tot1) % 60;
diff.hours = (tot2 - tot1) / 60;
return diff;
}
Time operator*(const Time &t, double n) {
Time result;
long totalminutes = t.hours*n * 60 + t.minutes*n;
result.hours = totalminutes / 60;
result.minutes = totalminutes % 60;
return result;
}
ostream & operator<<(ostream & os, const Time & t) {
os << t.hours << " Hours, " << t.minutes << " minutes.";
return os;
}
usetime3.cpp
#include<iostream>
#include"mytime3.h"
using namespace std;
int main() {
Time aida(3, 35);
Time tosca(2, 48);
Time temp;
cout << "Aida and Tosca:\n";
cout << aida << ";" << tosca << endl;
temp = aida + tosca;
temp = aida*1.17;
cout << "Aida*1.17: " << temp << endl;
cout << "10*Tosca: " << 10 * tosca << endl;
system("pause");
return 0;
}
5.重新编写Stonewt类（程序清单11.16和程序清单11.17），使它有一个状态成员，由该成员控制对象应转换为英石格式、整数磅格式还是浮点磅格式。重载<<运算符，使用它来替换show_stn()和show_lbs()方法。重载加法、减法和乘法运算符，以便可以对Stonewt值进行加、减、乘运算。编写一个使用所有类方法和友元的小程序，来测试这个类。
stonewt.h
// stonewt.h -- definition for the Stonewt class
#ifndef STONEWT_H_
#define STONEWT_H_
class Stonewt
{
private:
enum {Lbs_per_stn = 14}; // pounds per stone
int stone; // whole stones
double pds_left; // fractional pounds
double pounds; // entire weight in pounds
public:
Stonewt(double lbs); // constructor for double pounds
Stonewt(int stn, double lbs); // constructor for stone, lbs
Stonewt(); // default constructor
~Stonewt();
void show_lbs() const; // show weight in pounds format
void show_stn() const; // show weight in stone format
};
#endif
stonewt.cpp
// stonewt.cpp -- Stonewt methods
#include <iostream>
using std::cout;
#include "stonewt.h"
// construct Stonewt object from double value
Stonewt::Stonewt(double lbs)
{
stone = int (lbs) / Lbs_per_stn; // integer division
pds_left = int (lbs) % Lbs_per_stn + lbs - int(lbs);
pounds = lbs;
}
// construct Stonewt object from stone, double values
Stonewt::Stonewt(int stn, double lbs)
{
stone = stn;
pds_left = lbs;
pounds = stn * Lbs_per_stn +lbs;
}
Stonewt::Stonewt() // default constructor, wt = 0
{
stone = pounds = pds_left = 0;
}
Stonewt::~Stonewt() // destructor
{
}
// show weight in stones
void Stonewt::show_stn() const
{
cout << stone << " stone, " << pds_left << " pounds\n";
}
// show weight in pounds
void Stonewt::show_lbs() const
{
cout << pounds << " pounds\n";
}
stone.cpp
// stone.cpp -- user-defined conversions
// compile with stonewt.cpp
#include <iostream>
using std::cout;
#include "stonewt.h"
void display(const Stonewt & st, int n);
int main()
{
Stonewt pavarotti = 260; // uses constructor to initialize
Stonewt wolfe(285.7); // same as Stonewt wolfe = 285.7;
Stonewt taft(21, 8);
cout << "The tenor weighed ";
pavarotti.show_stn();
cout << "The detective weighed ";
wolfe.show_stn();
cout << "The President weighed ";
taft.show_lbs();
pavarotti = 265.8; // uses constructor for conversion
taft = 325;
cout << "After dinner, the tenor weighed ";
pavarotti.show_stn();
cout << "After dinner, the President weighed ";
taft.show_lbs();
display(taft, 2);
cout << "The wrestler weighed even more.\n";
display(422, 2);
cout << "No stone left unearned\n";
system("pause");
return 0;
}
void display(const Stonewt & st, int n)
{
for (int i = 0; i < n; i++)
{
cout << "Wow! ";
st.show_stn();
}
}
7.复数有两个部分组成：实数部分和虚数部分。复数的一种书写方式是：（3.0,4.0）。请定义一个复数类，以便下面的程序可以使用它来获得正确的结果。
（……代码省略……）
注意。必须重载运算符<<和>>。标准C++使用头文件complex提供了比这个示例更广泛的复数支持，因此应将自定义的头文件命名为complex0.h，以免发生冲突。应尽可能使用const。
请注意，经过重载后，cin>>c将提示用户输入实数和虚数部分。
complex0.h
#pragma once
#include<iostream>
#ifndef COM0_H_
using namespace std;
class complex {
double a;
double b;
public:
complex();
complex(double x, double y);
~complex();
complex operator+(const complex & t) const;
complex operator-(const complex & t) const;
friend complex operator*(const complex & t,double n);//Êý³Ë
friend complex operator*(const complex & t1, const complex & t2);
friend complex operator~(const complex & t);
friend ostream & operator<<(ostream & os, const complex & c);
friend istream & operator >> (istream &in, complex &c);
};
#endif // !COM0_H_
complex0.cpp
#include "complex0.h"
#include<iostream>
complex::complex() {
a = 0;
b = 0;
}
complex::complex(double x, double y) {
a = x;
b = y;
}
complex::~complex() {}
complex complex::operator+(const complex & t) const
{
complex sum;
sum.a = a + t.a;
sum.b = b + t.b;
return sum;
}
complex complex::operator-(const complex & t) const
{
complex diff;
diff.a = a - t.a;
diff.b = b - t.b;
return diff;
}
complex operator*(const complex & t, double n) //Êý³Ë
{
return complex((t.a)*n, (t.b)*n);
}
complex operator*(const complex & t1, const complex & t2)
{
return complex((t1.a*t2.a - t1.b*t2.b), (t1.a*t2.b + t1.b*t2.a));
}
complex operator~(const complex & t)
{
return complex(t.a, (-1.0)*t.b);
}
ostream & operator<<(ostream & os, const complex & c)
{
os << "(" << c.a << "," << c.b << "!" << ")";
return os;
}
istream & operator >> (istream &in, complex &c)
{
in >> c.a >> c.b;
return in;
}
备注：
操作系统：Windows 10 x64(1803)
编译器：Microsoft Visual Studio 2015
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