C++ Primer Plus 第十五章（15章）编程题答案

习题1 （15.8.1）细节上“状态成员”没有放在remote类里，切换状态成员的我放在remote里了，原理一样。

//标头.h

#pragma once

#ifndef INTERTV_H_

#define INTERTV_H_

#include <iostream>

using namespace std;

class Tv;

enum Tv_mode { Regular, Interact };

class Remote

{

   friend class Tv;

private:



public:



   void Show_mode(Tv & t);

   void SET_MODE(Tv & t, Tv_mode form);

   void Change_MODE(Tv & t);

};

class Tv

{

   friend class Remote;

private:

   Tv_mode Mode;

public:

   Tv(Tv_mode M = Regular) {};



};

void Remote::SET_MODE(Tv & t, Tv_mode form )

{

   t.Mode = form;

}

void Remote::Show_mode(Tv & t)

{

   if (t.Mode == Regular) cout << "Now is Regular mode.\n";

   else cout << "Now is interactive mode.\n";

}

void Remote::Change_MODE(Tv& t)

{

   t.Mode = (t.Mode == Regular) ? Interact : Regular;

}

#endif

//15.8.1.cpp

#include "stdafx.h"

#include "标头.h"

int main()

{

   Tv Tv1;

   Remote Remote1;

   Remote1.Show_mode(Tv1);

   Remote1.Change_MODE(Tv1);

   Remote1.Show_mode(Tv1);

   Remote1.SET_MODE(Tv1, Interact);

   Remote1.Show_mode(Tv1);

    return 0;

}

习题2 15.8.2

//标头.h

#pragma once

#include <iostream>

#include <stdexcept>

#include <exception>

#include <string>

class bad_hmean :public std::logic_error

{

private:

   double v1;

   double v2;

public:

   bad_hmean(double a = 0, double b = 0) : v1(a), v2(b),logic_error("function name: bad_hmean. Logic Error.") {}

   void mesg();

   const char * what()

   {

       return "function name: bad_hmean. Logic Error.";

   }

};

inline void bad_hmean::mesg()

{

   std::cout << "hmean(" << v1 << ", " << v2 << "): "

       << "invalid arguments: a = -b\n";

}

class bad_gmean :public std::logic_error

{

public:

   double v1;

   double v2;

   bad_gmean(double a = 0, double b = 0) : v1(a), v2(b), logic_error("function name: bad_hmean. Logic Error.") {}

   const char * mesg();

   const char * what()

   {

       return "function name: bad_gmean. Logic Error.";

   }

};

inline const char * bad_gmean::mesg()

{

   return "gmean() arguments should be >= 0\n";

}

// 15.8.2.cpp: 定义控制台应用程序的入口点。

//

#include "stdafx.h"

#include <iostream>

#include <cmath> // or math.h, unix users may need -lm flag

#include "标头.h"

// function prototypes

double hmean(double a, double b);

double gmean(double a, double b);

int main()

{

   using std::cout;

   using std::cin;

   using std::endl;

   double x, y, z;

   cout << "Enter two numbers: ";

   while (cin >> x >> y)

   {

       try {                  // start of try block

           z = hmean(x, y);

           cout << "Harmonic mean of " << x << " and " << y

               << " is " << z << endl;

           cout << "Geometric mean of " << x << " and " << y

               << " is " << gmean(x, y) << endl;

           cout << "Enter next set of numbers <q to quit>: ";

       }// end of try block

       catch (bad_hmean & bg)    // start of catch block

       {

           bg.mesg();

           cout << "Try again.\n";

           cout << bg.what();

           continue;

       }

       catch (bad_gmean & hg)

       {

           cout << hg.mesg();

           cout << "Values used: " << hg.v1 << ", "

               << hg.v2 << endl;

           cout << hg.what();

           cout << "Sorry, you don't get to play any more.\n";

           break;

       } // end of catch block

   }

   cout << "Bye!\n";

   // cin.get();

   // cin.get();

   return 0;

}

double hmean(double a, double b)

{

   if (a == -b)

       throw bad_hmean(a, b);

   return 2.0 * a * b / (a + b);

}

double gmean(double a, double b)

{

   if (a < 0 || b < 0)

       throw bad_gmean(a, b);

   return std::sqrt(a * b);

}

习题3. 15.8.3

#pragma once

//标头.h

#ifndef STDEXCEPT_H_

#define STDEXCEPT_H_

#include "stdafx.h"

#include <stdexcept>

#include <iostream>

using namespace std;

class bad_hmean :public std::logic_error

{

private:

   double v1;

   double v2;

public:

   bad_hmean(double a = 0, double b = 0) : v1(a), v2(b), logic_error("function name: bad_hmean. Logic Error.") {}

   void mesg();

   void just_report();

   void * what()

   {

       cout << "function name: bad_hmean.";

       cout << "Values: (" << v1 << "," << v2 << ")\n";

   }

};

void bad_hmean::just_report()

{

   std::cout << "hmean(" << v1 << ", " << v2 << "): ";

}

inline void bad_hmean::mesg()

{

   std::cout << "hmean(" << v1 << ", " << v2 << "): "

       << "invalid arguments: a = -b\n";

}

class bad_gmean :public std::logic_error

{

public:

   double v1;

   double v2;

   bad_gmean(double a = 0, double b = 0) : v1(a), v2(b), logic_error("function name: bad_hmean. Logic Error.") {}

   void just_report();

   const char * mesg();

   void * what()

   {

       cout << "function name: bad_hmean.";

       cout << "Values: (" << v1 << "," << v2 << ")\n";

   }

};

void bad_gmean::just_report()

{

   std::cout << "gmean(" << v1 << ", " << v2 << "): ";

}

inline const char * bad_gmean::mesg()

{

   return "gmean() arguments should be >= 0\n";

}

#endif

// 15.8.3.cpp

#include "stdafx.h"

#include "标头.h"

double hmean(double a, double b);

double gmean(double a, double b);

int main()

{

   using std::cout;

   using std::cin;

   using std::endl;

   double x, y, z;

   cout << "Enter two numbers: ";

   while (cin >> x >> y)

   {

       try {                  // start of try block

           z = hmean(x, y);

           cout << "Harmonic mean of " << x << " and " << y

               << " is " << z << endl;

           cout << "Geometric mean of " << x << " and " << y

               << " is " << gmean(x, y) << endl;

           cout << "Enter next set of numbers <q to quit>: ";

       }// end of try block

       catch (std::logic_error & bg)    // start of catch block

       {

           bg.what();

           cout << "End of the loop.";



           break;

       }



   }

   cout << "Bye!\n";

   // cin.get();

   // cin.get();

   return 0;

}

double hmean(double a, double b)

{

   if (a == -b)

       throw bad_hmean(a, b);

   return 2.0 * a * b / (a + b);

}

double gmean(double a, double b)

{

   if (a < 0 || b < 0)

       throw bad_gmean(a, b);

   return std::sqrt(a * b);

}

习题4. 15.8.4

//标头.h

#pragma once

#include <stdexcept>

#include <string>

class Sales

{

public:

   enum { MONTHS = 12 };   // could be a static const

   class bad_index : public std::logic_error

   {

   private:

       int bi; // bad index value

   public:

       explicit bad_index(int ix,

           const std::string & s = "Index error in Sales object\n");

       int bi_val() const { return bi; }

       virtual ~bad_index() throw() {}

   };

   explicit Sales(int yy = 0);

   Sales(int yy, const double * gr, int n);

   virtual ~Sales() { }

   int Year() const { return year; }

   virtual double operator[](int i) const;

   virtual double & operator[](int i);

private:

   double gross[MONTHS];

   int year;

};

class LabeledSales : public Sales

{

public:

   class nbad_index : public Sales::bad_index

   {

   private:

       std::string lbl;

   public:

       nbad_index(const std::string & lb, int ix,

           const std::string & s = "Index error in LabeledSales object\n");

       const std::string & label_val() const { return lbl; }

       virtual ~nbad_index() throw() {}

   };

   explicit LabeledSales(const std::string & lb = "none", int yy = 0);

   LabeledSales(const std::string & lb, int yy, const double * gr, int n);

   virtual ~LabeledSales() { }

   const std::string & Label() const { return label; }

   virtual double operator[](int i) const;

   virtual double & operator[](int i);

private:

   std::string label;

};

// 源.cpp -- Sales implementation

#include "stdafx.h"

#include "标头.h"

using std::string;

Sales::bad_index::bad_index(int ix, const string & s)

   : std::logic_error(s), bi(ix)

{

}

Sales::Sales(int yy)

{

   year = yy;

   for (int i = 0; i < MONTHS; ++i)

       gross[i] = 0;

}

Sales::Sales(int yy, const double * gr, int n)

{

   year = yy;

   int lim = (n < MONTHS) ? n : MONTHS;

   int i;

   for (i = 0; i < lim; ++i)

       gross[i] = gr[i];

   // for i > n and i < MONTHS

   for (; i < MONTHS; ++i)

       gross[i] = 0;

}

double Sales::operator[](int i) const

{

   if (i < 0 || i >= MONTHS)

       throw bad_index(i);

   return gross[i];

}

double & Sales::operator[](int i)

{

   if (i < 0 || i >= MONTHS)

       throw bad_index(i);

   return gross[i];

}

LabeledSales::nbad_index::nbad_index(const string & lb, int ix,

   const string & s) : Sales::bad_index(ix, s)

{

   lbl = lb;

}

LabeledSales::LabeledSales(const string & lb, int yy)

   : Sales(yy)

{

   label = lb;

}

LabeledSales::LabeledSales(const string & lb, int yy, const double * gr, int n)

   : Sales(yy, gr, n)

{

   label = lb;

}

double LabeledSales::operator[](int i) const

{

   if (i < 0 || i >= MONTHS)

       throw nbad_index(Label(), i);

   return Sales::operator[](i);

}

double & LabeledSales::operator[](int i)

{

   if (i < 0 || i >= MONTHS)

       throw nbad_index(Label(), i);

   return Sales::operator[](i);

}

// 15.8.4.cpp: 定义控制台应用程序的入口点。

//

#include "stdafx.h"

// use_sales.cpp -- nested exceptions

#include <iostream>

#include "标头.h"

int main()

{

   using std::cout;

   using std::cin;

   using std::endl;

   double vals1[12] =

   {

       1220, 1100, 1122, 2212, 1232, 2334,

       2884, 2393, 3302, 2922, 3002, 3544

   };

   double vals2[12] =

   {

       12, 11, 22, 21, 32, 34,

       28, 29, 33, 29, 32, 35

   };

   Sales sales1(2011, vals1, 12);

   LabeledSales sales2("Blogstar", 2012, vals2, 12);

   cout << "First try block:\n";

   try

   {

       int i;

       cout << "Year = " << sales1.Year() << endl;

       for (i = 0; i < 12; ++i)

       {

           cout << sales1[i] << ' ';

           if (i % 6 == 5)

               cout << endl;

       }

       cout << "Year = " << sales2.Year() << endl;

       cout << "Label = " << sales2.Label() << endl;

       for (i = 0; i <= 12; ++i)

       {

           cout << sales2[i] << ' ';

           if (i % 6 == 5)

               cout << endl;

       }

       cout << "End of try block 1.\n";

   }

   catch (Sales::bad_index & bad)

   {

       Sales::bad_index * pt = &bad;

       if (LabeledSales::nbad_index * ptlb = dynamic_cast<LabeledSales::nbad_index *> (pt))

           cout << "Company: " << ptlb->label_val() << endl;

       cout << bad.what();

       cout << "bad index: " << bad.bi_val() << endl;

   }

   cout << "\nNext try block:\n";

   try

   {

       sales2[2] = 37.5;

       sales1[20] = 23345;

       cout << "End of try block 2.\n";

   }

   catch (LabeledSales::nbad_index & bad)

   {

       cout << bad.what();

       cout << "Company: " << bad.label_val() << endl;

       cout << "bad index: " << bad.bi_val() << endl;

   }

   catch (Sales::bad_index & bad)

   {

       cout << bad.what();

       cout << "bad index: " << bad.bi_val() << endl;

   }

   cout << "done\n";

   // std::cin.get();

   return 0;

}

C++ Primer Plus 第十五章 （15章） 编程题答案

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C++ Primer Plus 第十五章（15章）编程题答案