C++ Primer Plus 第六版第十二章课后编程练习答案

2017-10-30 1条评论 6,244次阅读 3人点赞

编译环境Visual Studio 2017

// Chapter12.h
#pragma once
#ifndef CHAPTER12_H_
#define CHAPTER12_H_

class Cow {
    char name[20];
    char * hobby;
    double weight;

public:
    Cow();
    Cow(const char * nm, const char * ho, double wt);
    Cow(const Cow & c);
    ~Cow();
    Cow & operator=(const Cow & c);
    void ShowCow() const;
};

#endif // !CHAPTER12_H_


// Chapter12.cpp
#include <iostream>
#include <string>
#include <cstring>
#include <cctype>
#include <cmath>
#include <ctime>
#include <cstdlib>

#include "Chapter12.h"
#include "string2.h"
#include "Stock.h"
#include "Stack.h"
#include "Queue.h"

using namespace std;


// practice 1
Cow::Cow()
{

}
Cow::Cow(const char * nm, const char * ho, double wt)
{
    strncpy(name, nm, 20);
    int ho_length = strlen(ho);
    hobby = new char[ho_length + 1];
    strncpy(hobby, ho, ho_length);
    hobby[ho_length] = '\0';
    weight = wt;
}
Cow::Cow(const Cow & c)
{
    strncpy(name, c.name, 20);
    int ho_length = strlen(c.hobby);
    hobby = new char[ho_length + 1];
    strncpy(hobby, c.hobby, ho_length);
    hobby[ho_length] = '\0';
    weight = c.weight;
}
Cow::~Cow()
{
    delete[] hobby;
    hobby = nullptr;
}
Cow & Cow::operator=(const Cow & c)
{
    strncpy(name, c.name, 20);
    int ho_length = strlen(c.hobby);
    hobby = new char[ho_length + 1];
    strncpy(hobby, c.hobby, ho_length);
    hobby[ho_length] = '\0';
    weight = c.weight;

    return *this;
}
void Cow::ShowCow() const
{
    cout << "Cow name: " << name << endl;
    cout << "Cow hobby: " << hobby << endl;
    cout << "Cow weight: " << weight << endl;
}
void p12_1(void)
{
    Cow cow1("hehehe", "eat", 123.4);
    Cow cow2("heihei", "drink", 321.2);
    Cow cow3(cow2);
    Cow cow4 = cow1;

    cow1.ShowCow();
    cow2.ShowCow();
    cow3.ShowCow();
    cow4.ShowCow();
}


// practice 2
void p12_2(void)
{
    String2 s1("and i am a C++ student.");
    String2 s2 = "Please enter your name: ";
    String2 s3;
    cout << s2;
    cin >> s3;
    s2 = "My name is " + s3;
    cout << s2 << ".\n";
    s2 = s2 + s1;
    s2.Stringup();
    cout << "The sting\n" << s2 << "\ncontains " << s2.has('A')
        << " 'A' characters in it.\n";
    s1 = "red";
    String2 rgb[3] = { String2(s1), String2("green"), String2("blue") };
    cout << "Enter the name of a primary color for mixing light: ";
    String2 ans;
    bool success = false;
    while (cin >> ans)
    {
        ans.Stringlow();
        for (int i = 0; i < 3; i++)
        {
            if (ans == rgb[i])
            {
                cout << "That's right!\n";
                success = true;
                break;
            }
        }
        if (success)
        {
            break;
        }
        else
        {
            cout << "Try again!\n";
        }
    }

    cout << "Bye!\n";
    return ;
}


// practice 3
const int STKS = 4;
void p12_3(void)
{
    Stock stocks[STKS] = {
        Stock("NanoSmart", 12, 20.0),
        Stock("Boffo Objects", 200, 2.0),
        Stock("Monolithic Obelisks", 130, 3.25),
        Stock("Fleep Enterprises", 60, 6.5)
    };

    std::cout << "Stock holdings:\n";
    int st;
    for (st = 0; st < STKS; st++)
    {
        std::cout << stocks[st];
    }

    const Stock * top = &stocks[0];
    for (st = 0; st < STKS; st++)
    {
        top = &top->topval(stocks[st]);
    }

    std::cout << "\nMost valuable holding:\n";
    cout << *top;
    return;
}


// practice 4
void p12_4(void)
{
    Stack st1(10);
    srand(time(0));
    for (size_t i = 0; i < 10; i++)
    {
        if (!st1.push(rand() % 100))
        {
            cout << "Push error!" << endl;;
        }

    }
    if (!st1.push(0))
    {
        cout << "Push 0 error!" << endl;
    }
    Stack st2(st1);
    Stack st3 = st1;
    // 故意导致pop error
    for (size_t i = 0; i < 11; i++)
    {
        Item item;
        cout << "#" << i+1 << ": " << endl;
        if (!st1.pop(item))
        {
            cout << "st1 pop error!" << endl;
        }
        else
            cout << "st1: " << item << endl;

        if (!st2.pop(item))
        {
            cout << "st2 pop error!" << endl;
        }
        else
            cout << "st2: " << item << endl;

        if (!st3.pop(item))
        {
            cout << "st3 pop error!" << endl;
        }
        else
            cout << "st3: " << item << endl;

        cout << endl;
    }
}


// practice 5
const int MIN_PER_HR = 60;
bool newcustomer(double x)
{
    return (std::rand() * x / RAND_MAX < 1);
}
void p12_5(void)
{
    using std::cin;
    using std::cout;
    using std::endl;
    using std::ios_base;

    std::srand(std::time(0));

    cout << "Case Study: Bank of Heather Automatic Teller\n";
    cout << "Enter maximun size of queue: ";
    int qs;
    cin >> qs;
    Queue line(qs);

    // 直接将测试时间设置为100好了
    cout << "Simulation hours: 100" << endl;
    int hours = 100;

    long cyclelimit = MIN_PER_HR * hours;

    cItem temp;
    long turnaways = 0;
    long customers = 0;
    long served = 0;
    long sum_line = 0;
    int wait_time = 0;
    long line_wait = 0;
    double avg_wait_time = 0.0;

    // 每小时使用人数初始值为15，之后进行+1枚举测试
    double perhour = 15;
    double min_per_cust;

    do {
        min_per_cust = MIN_PER_HR / perhour;
        turnaways = 0;
        customers = 0;
        served = 0;
        sum_line = 0;
        wait_time = 0;
        line_wait = 0;
        avg_wait_time = 0;

        // 需要清空队列
        while (!line.isempty())
        {
            line.dequeue(temp);
        }

        for (int cycle = 0; cycle < cyclelimit; cycle++)
        {
            if (newcustomer(min_per_cust))
            {
                if (line.isfull())
                {
                    turnaways++;
                }
                else
                {
                    customers++;
                    temp.set(cycle);
                    line.enqueue(temp);
                }
            }
            if (wait_time <= 0 && !line.isempty())
            {
                line.dequeue(temp);
                wait_time = temp.ptime();
                line_wait += (cycle - temp.when());
                served++;
            }
            if (wait_time > 0)
            {
                wait_time--;
            }
            sum_line += line.queuecount();
        }

        if (customers > 0)
        {
            cout << "customers accepted: " << customers << endl;
            cout << "  customers served: " << served << endl;
            cout << "         turnaways: " << turnaways << endl;
            cout << "average queue size: ";
            cout.precision(2);
            cout.setf(ios_base::fixed, ios_base::floatfield);
            cout << (double)sum_line / cyclelimit << endl;
            avg_wait_time = (double)line_wait / served;
            cout << " average wait time: "
                << avg_wait_time << " minutes\n" << endl;
        }
        else
            cout << "No customers!\n" << endl;;
        // 平均等待时间不一定刚好是1，设置在一个区间内
    } while ((perhour++) && (avg_wait_time < 0.9) || (avg_wait_time > 1.1));

    cout << "When perhour = " << perhour << " , the average wait time"
        " will be about 1 minute\n" << endl;

    cout << "Done!\n";

    return;
}


// practice 6
void p12_6(void)
{
    using std::cin;
    using std::cout;
    using std::endl;
    using std::ios_base;

    std::srand(std::time(0));

    cout << "Case Study: Bank of Heather Automatic Teller\n";
    cout << "Enter maximun size of queue: ";
    int qs;
    cin >> qs;
    Queue line1(qs);
    Queue line2(qs);

    // 直接将测试时间设置为100好了
    cout << "Simulation hours: 100" << endl;
    int hours = 100;

    long cyclelimit = MIN_PER_HR * hours;

    cItem temp;
    long turnaways = 0;
    long customers = 0;
    long served = 0;
    long sum_line = 0;
    int wait_time1 = 0;
    int wait_time2 = 0;
    int line1_size = 0;
    int line2_size = 0;
    long line_wait = 0;
    double avg_wait_time = 0.0;

    // 每小时使用人数初始值为15，之后进行+1枚举测试
    double perhour = 15;
    double min_per_cust;

    do {
        min_per_cust = MIN_PER_HR / perhour;
        turnaways = 0;
        customers = 0;
        served = 0;
        sum_line = 0;
        wait_time1 = 0;
        wait_time2 = 0;
        line1_size = 0;
        line2_size = 0;
        line_wait = 0;
        avg_wait_time = 0;

        // 需要清空队列
        while (!line1.isempty())
        {
            line1.dequeue(temp);
        }

        while (!line2.isempty())
        {
            line2.dequeue(temp);
        }

        for (int cycle = 0; cycle < cyclelimit; cycle++)
        {
            if (newcustomer(min_per_cust))
            {
                if (line1.isfull() && line2.isfull())
                {
                    turnaways++;
                }
                else if (line1_size > line2_size)
                {
                    customers++;
                    temp.set(cycle);
                    line2.enqueue(temp);
                    line2_size++;
                } 
                else
                {
                    customers++;
                    temp.set(cycle);
                    line1.enqueue(temp);
                    line1_size++;
                }
            }
            if (wait_time1 <= 0 && !line1.isempty())
            {
                line1.dequeue(temp);
                line1_size--;
                wait_time1 = temp.ptime();
                line_wait += (cycle - temp.when());
                served++;
            }
            if (wait_time2 <=0 && !line2.isempty())
            {
                line2.dequeue(temp);
                line2_size--;
                wait_time2 = temp.ptime();
                line_wait += (cycle - temp.when());
                served++;
            }
            if (wait_time1 > 0)
            {
                wait_time1--;
            }
            if (wait_time2 > 0)
            {
                wait_time2--;
            }
            sum_line += line1.queuecount();
            sum_line += line2.queuecount();
        }

        if (customers > 0)
        {
            cout << "customers accepted: " << customers << endl;
            cout << "  customers served: " << served << endl;
            cout << "         turnaways: " << turnaways << endl;
            cout << "average queue size: ";
            cout.precision(2);
            cout.setf(ios_base::fixed, ios_base::floatfield);
            cout << (double)sum_line / cyclelimit << endl;
            avg_wait_time = (double)line_wait / served;
            cout << " average wait time: "
                << avg_wait_time << " minutes\n" << endl;;
        }
        else
            cout << "No customers!\n" << endl;
        // 平均等待时间不一定刚好是1，设置在一个区间内
    } while ((perhour++) && (avg_wait_time < 0.9) || (avg_wait_time > 1.1));

    cout << "When perhour = " << perhour << " , the average wait time"
        " will be about 1 minute\n" << endl;

    cout << "Done!\n";

    return;
}


int main(int argc, char **argv)
{
    p12_6();

    while (cin.get());
}


// Queue.h
#pragma once

class Customer
{
private:
    long arrive;
    int processtime;

public:
    Customer() { arrive = processtime = 0; }
    void set(long when);
    long when() const { return arrive; }
    int ptime() const { return processtime; }
};

typedef Customer cItem;

class Queue
{
private:
    struct Node { cItem item; struct Node * next; };
    enum {Q_SIZE = 10};
    Node * front;
    Node * rear;
    int items;
    const int qsize;
    Queue(const Queue & q) : qsize(0) {}
    Queue & operator=(const Queue & q) { return *this; }

public:
    Queue(int qs = Q_SIZE);
    ~Queue();
    bool isempty() const;
    bool isfull() const;
    int queuecount() const;
    bool enqueue(const cItem & item);
    bool dequeue(cItem & item);
};


// Queue.cpp
#include "Queue.h"
#include <cstdlib>


Queue::Queue(int qs) : qsize(qs)
{
    front = rear = NULL;
    items = 0;
}

Queue::~Queue()
{
    Node * temp;
    while (front != NULL)
    {
        temp = front;
        front = front->next;
        delete temp;
    }
}

bool Queue::isempty() const
{
    return items == 0;
}

bool Queue::isfull() const
{
    return items == qsize;
}

int Queue::queuecount() const
{
    return items;
}

bool Queue::enqueue(const cItem & item)
{
    if (isfull())
    {
        return false;
    }

    Node * add = new Node;
    add->item = item;
    add->next = NULL;
    items++;
    if (front == NULL)
    {
        front = add;
    }
    else
        rear->next = add;

    rear = add;
    return true;
}

bool Queue::dequeue(cItem & item)
{
    if (front == NULL)
    {
        return false;
    }

    item = front->item;
    items--;
    Node * temp = front;
    front = front->next;
    delete temp;

    if (items == 0)
    {
        rear = NULL;
    }
    return true;
}

void Customer::set(long when)
{
    processtime = std::rand() % 3 + 1;
    arrive = when;
}


// Stack.h
#pragma once
typedef unsigned long Item;


class Stack
{
private:
    enum {MAX = 10};
    Item * pitems;
    int size;
    int top;

public:
    Stack(int n = MAX);
    Stack(const Stack & st);
    ~Stack();
    bool isempty() const;
    bool isfull() const;
    bool push(const Item & item);
    bool pop(Item & item);
    Stack & operator=(const Stack & st);
};


// Stack.cpp
#include "Stack.h"
#include <iostream>


Stack::Stack(int n)
{
    pitems = new Item[n];
    size = n;
    top = 0;
}

Stack::Stack(const Stack & st)
{
    size = st.size;
    pitems = new Item[size];
    top = st.top;
    for (int i = 0; i < top; i++)
    {
        pitems[i] = st.pitems[i];
    }
}

Stack::~Stack()
{
    delete[] pitems;
    pitems = nullptr;
}

bool Stack::isempty() const
{
    return top == 0;
}

bool Stack::isfull() const
{
    return top == size;
}

bool Stack::push(const Item & item)
{
    if (isfull())
    {
        return false;
    }

    pitems[top++] = item;
    return true;
}

bool Stack::pop(Item & item)
{
    if (isempty())
    {
        return false;
    }

    item = pitems[--top];
    return true;
}

Stack & Stack::operator=(const Stack & st)
{
    size = st.size;
    pitems = new Item[size];
    top = st.top;
    for (int i = 0; i < top; i++)
    {
        pitems[i] = st.pitems[i];
    }

    return *this;
}


// Stock.h
#pragma once
#include <iostream>
class Stock
{
private:
    char * company;
    int shares;
    double share_val;
    double total_val;
    void set_tot() { total_val = shares * share_val; }

public:
    Stock();
    Stock(const char * co, long n = 0, double pr = 0.0);
    ~Stock();
    void buy(long num, double price);
    void sell(long num, double price);
    void update(double price);
    void show() const;
    friend std::ostream & operator<<(std::ostream & os, const Stock & st);
    const Stock & topval(const Stock & s) const;
};


// Stock.cpp
#include "Stock.h"
#include <cstring>


Stock::Stock()
{
    int len = std::strlen("no name");
    company = new char[len + 1];
    std::strcpy(company, "no name");
    company[len] = '\0';

    shares = 0;
    share_val = 0.0;
    total_val = 0.0;
}

Stock::Stock(const char * co, long n, double pr)
{
    int len = std::strlen(co);
    company = new char[len + 1];
    std::strcpy(company, co);

    if (n < 0)
    {
        std::cout << "Number of shares can't be negative; "
            << company << " shares set to n.\n";
        shares = 0;
    }
    else
        shares = n;
    share_val = pr;
    set_tot();
}

Stock::~Stock()
{
    delete[] company;
    company = nullptr;
}

void Stock::buy(long num, double price)
{
    if (num < 0)
    {
        std::cout << "Number of shares purchased can't be negative. "
            << "Transaction is aborted.\n";
    }
    else
    {
        shares += num;
        share_val = price;
        set_tot();
    }
}

void Stock::sell(long num, double price)
{
    using std::cout;
    if (num < 0)
    {
        cout << "Number of shares sold can't be negative. "
            << "Transaction is aborted.\n";
    }
    else if (num > shares)
    {
        cout << "You can't sell more than you have! "
            << "Transaction is aborted.\n";
    }
    else
    {
        shares -= num;
        share_val = price;
        set_tot();
    }
}

void Stock::update(double price)
{
    share_val = price;
    set_tot();
}

void Stock::show() const
{
    using std::cout;
    using std::ios_base;
    ios_base::fmtflags orig =
        cout.setf(ios_base::fixed, ios_base::floatfield);
    std::streamsize prec = cout.precision(3);

    cout << "Company: " << company
        << " Shares: " << shares << '\n';
    cout << "Share Price: $" << share_val;
    cout.precision(2);
    cout << " Total Worth: $" << total_val << '\n';

    cout.setf(orig, ios_base::floatfield);
    cout.precision(prec);
}

std::ostream & operator<<(std::ostream & os, const Stock & st)
{
    using std::ios_base;
    ios_base::fmtflags orig =
        os.setf(ios_base::fixed, ios_base::floatfield);
    std::streamsize prec = os.precision(3);

    os << "Company: " << st.company
        << " Shares: " << st.shares << '\n';
    os << " Share Price: $" << st.share_val;
    os.precision(2);
    os << " Total Worth: $" << st.total_val << '\n';

    os.setf(orig, ios_base::floatfield);
    os.precision(prec);

    return os;
}

const Stock & Stock::topval(const Stock & s) const
{
    if (s.total_val > total_val)
    {
        return s;
    }
    else
        return *this;
}


// string2.h
#pragma once
#ifndef STRING2_H_
#define STRING2_H_

#include <iostream>
using std::ostream;
using std::istream;

class String2
{
private:
    char * str;
    int len;
    static int num_strings;
    static const int CINLIM = 80;

public:
    String2(const char * s);
    String2();
    String2(const String2 &);
    ~String2();
    int length() const { return len; }

    String2 & operator=(const String2 &);
    String2 & operator=(const char *);
    char & operator[](int i);
    const char & operator[](int i) const;

    friend bool operator<(const String2 &st, const String2 &st2);
    friend bool operator>(const String2 &st, const String2 &st2);
    friend bool operator==(const String2 &st, const String2 &st2);
    friend ostream & operator<<(ostream & os, const String2 &st);
    friend istream & operator>>(istream & is, String2 &st);

    static int HowMany();

    String2 operator+(const String2 &) const;
    String2 operator+(const char *) const;
    friend String2 operator+(const char *, const String2 &);
    void Stringlow();
    void Stringup();
    int has(char);
};

#endif // !STRING2_H_


// string2.cpp
#include <cstring>
#include "string2.h"

using std::cin;
using std::cout;

int String2::num_strings = 0;

int String2::HowMany()
{
    return num_strings;
}

String2::String2(const char * s)
{
    len = std::strlen(s);
    str = new char[len + 1];
    std::strcpy(str, s);
    num_strings++;
}

String2::String2()
{
    len = 4;
    str = new char[1];
    str[0] = '\0';
    num_strings++;
}

String2::String2(const String2 & st)
{
    num_strings++;
    len = st.len;
    str = new char[len + 1];
    std::strcpy(str, st.str);
}

String2::~String2()
{
    --num_strings;
    delete[] str;
}

String2 & String2::operator=(const String2 & st)
{
    if (this == &st)
    {
        return *this;
    }
    delete[] str;
    len = st.len;
    str = new char[len + 1];
    std::strcpy(str, st.str);
    return *this;
}

String2 & String2::operator=(const char * s)
{
    delete[] str;
    len = std::strlen(s);
    str = new char[len + 1];
    std::strcpy(str, s);
    return *this;
}

char & String2::operator[](int i)
{
    return str[i];
}

const char & String2::operator[](int i) const
{
    return str[i];
}

bool operator<(const String2 & st, const String2 & st2)
{
    return(std::strcmp(st.str, st2.str) < 0);
}

bool operator>(const String2 & st, const String2 & st2)
{
    return(std::strcmp(st.str, st2.str) > 0);
}

bool operator==(const String2 & st, const String2 & st2)
{
    return(std::strcmp(st.str, st2.str) == 0);
}

ostream & operator<<(ostream & os, const String2 & st)
{
    os << st.str;
    return os;
}

istream & operator>>(istream & is, String2 & st)
{
    char temp[String2::CINLIM];
    is.get(temp, String2::CINLIM);
    if (is)
    {
        st = temp;
    }
    while (is && is.get() != '\n')
    {
        continue;
    }
    return is;
}

String2 String2::operator+(const String2 & st) const
{
    int total_len = len + st.len;
    char *temp = new char[total_len + 1];
    std::strcpy(temp, str);
    std::strcpy(temp + len, st.str);
    temp[total_len] = '\0';
    return String2(temp);
}

String2 String2::operator+(const char * s) const
{
    int total_len = len + strlen(s);
    char *temp = new char[total_len + 1];
    std::strcpy(temp, str);
    std::strcpy(temp + len, s);
    temp[total_len] = '\0';
    return String2(temp);
}

String2 operator+(const char * s, const String2 & st)
{
    return String2(s) + st;
}

void String2::Stringlow()
{
    for (int i = 0; i < len + 1; i++)
    {
        str[i] = tolower(str[i]);
    }
}

void String2::Stringup()
{
    for (int i = 0; i < len + 1; i++)
    {
        str[i] = toupper(str[i]);
    }
}

int String2::has(char c)
{
    int same = 0;
    for (int i = 0; i < len; i++)
    {
        if (str[i] == c)
        {
            same++;
        }
    }

    return same;
}

100

101

102

103

104

105

106

107

108

109

110

111

112

113

114

115

116

117

118

119

120

121

122

123

124

125

126

127

128

129

130

131

132

133

134

135

136

137

138

139

140

141

142

143

144

145

146

147

148

149

150

151

152

153

154

155

156

157

158

159

160

161

162

163

164

165

166

167

168

169

170

171

172

173

174

175

176

177

178

179

180

181

182

183

184

185

186

187

188

189

190

191

192

193

194

195

196

197

198

199

200

201

202

203

204

205

206

207

208

209

210

211

212

213

214

215

216

217

218

219

220

221

222

223

224

225

226

227

228

229

230

231

232

233

234

235

236

237

238

239

240

241

242

243

244

245

246

247

248

249

250

251

252

253

254

255

256

257

258

259

260

261

262

263

264

265

266

267

268

269

270

271

272

273

274

275

276

277

278

279

280

281

282

283

284

285

286

287

288

289

290

291

292

293

294

295

296

297

298

299

300

301

302

303

304

305

306

307

308

309

310

311

312

313

314

315

316

317

318

319

320

321

322

323

324

325

326

327

328

329

330

331

332

333

334

335

336

337

338

339

340

341

342

343

344

345

346

347

348

349

350

351

352

353

354

355

356

357

358

359

360

361

362

363

364

365

366

367

368

369

370

371

372

373

374

375

376

377

378

379

380

381

382

383

384

385

386

387

388

389

390

391

392

393

394

395

396

397

398

399

400

401

402

403

404

405

406

407

408

409

410

411

412

413

414

415

416

417

418

419

420

421

422

423

424

425

426

427

428

429

430

431

432

433

434

435

436

437

438

439

440

441

442

443

444

445

446

447

448

449

450

451

452

453

454

455

456

457

458

459

460

461

462

463

464

465

466

467

468

469

470

471

472

473

474

475

476

477

478

479

480

481

482

483

484

485

486

487

488

489

490

491

492

493

494

495

496

497

498

499

500

501

502

503

504

505

506

507

508

509

510

511

512

513

514

515

516

517

518

519

520

521

522

523

524

525

526

527

528

529

530

531

532

533

534

535

536

537

538

539

540

541

542

543

544

545

546

547

548

549

550

551

552

553

554

555

556

557

558

559

560

561

562

563

564

565

566

567

568

569

570

571

572

573

574

575

576

577

578

579

580

581

582

583

584

585

586

587

588

589

590

591

592

593

594

595

596

597

598

599

600

601

602

603

604

605

606

607

608

609

610

611

612

613

614

615

616

617

618

619

620

621

622

623

624

625

626

627

628

629

630

631

632

633

634

635

636

637

638

639

640

641

642

643

644

645

646

647

648

649

650

651

652

653

654

655

656

657

658

659

660

661

662

663

664

665

666

667

668

669

670

671

672

673

674

675

676

677

678

679

680

681

682

683

684

685

686

687

688

689

690

691

692

693

694

695

696

697

698

699

700

701

702

703

704

705

706

707

708

709

710

711

712

713

714

715

716

717

718

719

720

721

722

723

724

725

726

727

728

729

730

731

732

733

734

735

736

737

738

739

740

741

742

743

744

745

746

747

748

749

750

751

752

753

754

755

756

757

758

759

760

761

762

763

764

765

766

767

768

769

770

771

772

773

774

775

776

777

778

779

780

781

782

783

784

785

786

787

788

789

790

791

792

793

794

795

796

797

798

799

800

801

802

803

804

805

806

807

808

809

810

811

812

813

814

815

816

817

818

819

820

821

822

823

824

825

826

827

828

829

830

831

832

833

834

835

836

837

838

839

840

841

842

843

844

845

846

847

848

849

850

851

852

853

854

855

856

857

858

859

860

861

862

863

864

865

866

867

868

869

870

871

872

873

874

875

876

877

878

879

880

881

882

883

884

885

886

887

888

889

890

891

892

893

894

895

896

897

898

899

900

901

902

903

904

905

906

907

908

909

910

911

912

913

914

915

916

917

918

919

920

921

922

923

924

925

926

927

928

929

930

931

932

933

934

935

936

937

938

939

940

941

942

943

944

945

946

947

948

949

950

951

952

953

954

955

956

957

958

959

960

961

962

963

964

965

966

967

968

969

970

971

972

973

974

975

976

977

978

979

980

981

982

983

984

985

986

987

988

989

990

991

992

993

994

995

996

997

998

999

1000

1001

1002

1003

1004

1005

1006

1007

1008

1009

1010

1011

1012

1013

1014

1015

1016

1017

1018

1019

1020

1021

1022

1023

1024

1025

1026

1027

1028

1029

1030

1031

1032

1033

1034

1035

1036

1037

1038

1039

1040

1041

1042

1043

1044

1045

1046

1047

1048

1049

1050

1051

1052

1053

1054

1055

1056

1057

1058

1059

1060

1061

1062

1063

1064

1065

1066

1067

1068

1069

1070

1071

1072

1073

1074

1075

1076

1077

1078

1079

1080

1081

1082

1083

1084

// Chapter12.h

#pragma once

#ifndef CHAPTER12_H_

#define CHAPTER12_H_

class Cow {

char name[20];

char * hobby;

double weight;

public:

Cow();

Cow(const char * nm, const char * ho, double wt);

Cow(const Cow & c);

~Cow();

Cow & operator=(const Cow & c);

void ShowCow() const;

};

#endif // !CHAPTER12_H_

// Chapter12.cpp

#include <iostream>

#include <string>

#include <cstring>

#include <cctype>

#include <cmath>

#include <ctime>

#include <cstdlib>

#include "Chapter12.h"

#include "string2.h"

#include "Stock.h"

#include "Stack.h"

#include "Queue.h"

using namespace std;

// practice 1

Cow::Cow()

{

}

Cow::Cow(const char * nm, const char * ho, double wt)

{

strncpy(name, nm, 20);

int ho_length = strlen(ho);

hobby = new char[ho_length + 1];

strncpy(hobby, ho, ho_length);

hobby[ho_length] = '\0';

weight = wt;

}

Cow::Cow(const Cow & c)

{

strncpy(name, c.name, 20);

int ho_length = strlen(c.hobby);

hobby = new char[ho_length + 1];

strncpy(hobby, c.hobby, ho_length);

hobby[ho_length] = '\0';

weight = c.weight;

}

Cow::~Cow()

{

delete[] hobby;

hobby = nullptr;

}

Cow & Cow::operator=(const Cow & c)

{

strncpy(name, c.name, 20);

int ho_length = strlen(c.hobby);

hobby = new char[ho_length + 1];

strncpy(hobby, c.hobby, ho_length);

hobby[ho_length] = '\0';

weight = c.weight;

return *this;

}

void Cow::ShowCow() const

{

cout << "Cow name: " << name << endl;

cout << "Cow hobby: " << hobby << endl;

cout << "Cow weight: " << weight << endl;

}

void p12_1(void)

{

Cow cow1("hehehe", "eat", 123.4);

Cow cow2("heihei", "drink", 321.2);

Cow cow3(cow2);

Cow cow4 = cow1;

cow1.ShowCow();

cow2.ShowCow();

cow3.ShowCow();

cow4.ShowCow();

}

// practice 2

void p12_2(void)

{

String2 s1("and i am a C++ student.");

String2 s2 = "Please enter your name: ";

String2 s3;

cout << s2;

cin >> s3;

s2 = "My name is " + s3;

cout << s2 << ".\n";

s2 = s2 + s1;

s2.Stringup();

cout << "The sting\n" << s2 << "\ncontains " << s2.has('A')

<< " 'A' characters in it.\n";

s1 = "red";

String2 rgb[3] = { String2(s1), String2("green"), String2("blue") };

cout << "Enter the name of a primary color for mixing light: ";

String2 ans;

bool success = false;

while (cin >> ans)

{

ans.Stringlow();

for (int i = 0; i < 3; i++)

{

if (ans == rgb[i])

{

cout << "That's right!\n";

success = true;

break;

}

if (success)

{

break;

}

else

{

cout << "Try again!\n";

}

cout << "Bye!\n";

return ;

}

// practice 3

const int STKS = 4;

void p12_3(void)

{

Stock stocks[STKS] = {

Stock("NanoSmart", 12, 20.0),

Stock("Boffo Objects", 200, 2.0),

Stock("Monolithic Obelisks", 130, 3.25),

Stock("Fleep Enterprises", 60, 6.5)

};

std::cout << "Stock holdings:\n";

int st;

for (st = 0; st < STKS; st++)

{

std::cout << stocks[st];

}

const Stock * top = &stocks[0];

for (st = 0; st < STKS; st++)

{

top = &top->topval(stocks[st]);

}

std::cout << "\nMost valuable holding:\n";

cout << *top;

return;

}

// practice 4

void p12_4(void)

{

Stack st1(10);

srand(time(0));

for (size_t i = 0; i < 10; i++)

{

if (!st1.push(rand() % 100))

{

cout << "Push error!" << endl;;

}

if (!st1.push(0))

{

cout << "Push 0 error!" << endl;

}

Stack st2(st1);

Stack st3 = st1;

// 故意导致pop error

for (size_t i = 0; i < 11; i++)

{

Item item;

cout << "#" << i+1 << ": " << endl;

if (!st1.pop(item))

{

cout << "st1 pop error!" << endl;

}

else

cout << "st1: " << item << endl;

if (!st2.pop(item))

{

cout << "st2 pop error!" << endl;

}

else

cout << "st2: " << item << endl;

if (!st3.pop(item))

{

cout << "st3 pop error!" << endl;

}

else

cout << "st3: " << item << endl;

cout << endl;

}

// practice 5

const int MIN_PER_HR = 60;

bool newcustomer(double x)

{

return (std::rand() * x / RAND_MAX < 1);

}

void p12_5(void)

{

using std::cin;

using std::cout;

using std::endl;

using std::ios_base;

std::srand(std::time(0));

cout << "Case Study: Bank of Heather Automatic Teller\n";

cout << "Enter maximun size of queue: ";

int qs;

cin >> qs;

Queue line(qs);

// 直接将测试时间设置为100好了

cout << "Simulation hours: 100" << endl;

int hours = 100;

long cyclelimit = MIN_PER_HR * hours;

cItem temp;

long turnaways = 0;

long customers = 0;

long served = 0;

long sum_line = 0;

int wait_time = 0;

long line_wait = 0;

double avg_wait_time = 0.0;

// 每小时使用人数初始值为15，之后进行+1枚举测试

double perhour = 15;

double min_per_cust;

do {

min_per_cust = MIN_PER_HR / perhour;

turnaways = 0;

customers = 0;

served = 0;

sum_line = 0;

wait_time = 0;

line_wait = 0;

avg_wait_time = 0;

// 需要清空队列

while (!line.isempty())

{

line.dequeue(temp);

}

for (int cycle = 0; cycle < cyclelimit; cycle++)

{

if (newcustomer(min_per_cust))

{

if (line.isfull())

{

turnaways++;

}

else

{

customers++;

temp.set(cycle);

line.enqueue(temp);

}

if (wait_time <= 0 && !line.isempty())

{

line.dequeue(temp);

wait_time = temp.ptime();

line_wait += (cycle - temp.when());

served++;

}

if (wait_time > 0)

{

wait_time--;

}

sum_line += line.queuecount();

}

if (customers > 0)

{

cout << "customers accepted: " << customers << endl;

cout << " customers served: " << served << endl;

cout << " turnaways: " << turnaways << endl;

cout << "average queue size: ";

cout.precision(2);

cout.setf(ios_base::fixed, ios_base::floatfield);

cout << (double)sum_line / cyclelimit << endl;

avg_wait_time = (double)line_wait / served;

cout << " average wait time: "

<< avg_wait_time << " minutes\n" << endl;

}

else

cout << "No customers!\n" << endl;;

// 平均等待时间不一定刚好是1，设置在一个区间内

} while ((perhour++) && (avg_wait_time < 0.9) || (avg_wait_time > 1.1));

cout << "When perhour = " << perhour << " , the average wait time"

" will be about 1 minute\n" << endl;

cout << "Done!\n";

return;

}

// practice 6

void p12_6(void)

{

using std::cin;

using std::cout;

using std::endl;

using std::ios_base;

std::srand(std::time(0));

cout << "Case Study: Bank of Heather Automatic Teller\n";

cout << "Enter maximun size of queue: ";

int qs;

cin >> qs;

Queue line1(qs);

Queue line2(qs);

// 直接将测试时间设置为100好了

cout << "Simulation hours: 100" << endl;

int hours = 100;

long cyclelimit = MIN_PER_HR * hours;

cItem temp;

long turnaways = 0;

long customers = 0;

long served = 0;

long sum_line = 0;

int wait_time1 = 0;

int wait_time2 = 0;

int line1_size = 0;

int line2_size = 0;

long line_wait = 0;

double avg_wait_time = 0.0;

// 每小时使用人数初始值为15，之后进行+1枚举测试

double perhour = 15;

double min_per_cust;

do {

min_per_cust = MIN_PER_HR / perhour;

turnaways = 0;

customers = 0;

served = 0;

sum_line = 0;

wait_time1 = 0;

wait_time2 = 0;

line1_size = 0;

line2_size = 0;

line_wait = 0;

avg_wait_time = 0;

// 需要清空队列

while (!line1.isempty())

{

line1.dequeue(temp);

}

while (!line2.isempty())

{

line2.dequeue(temp);

}

for (int cycle = 0; cycle < cyclelimit; cycle++)

{

if (newcustomer(min_per_cust))

{

if (line1.isfull() && line2.isfull())

{

turnaways++;

}

else if (line1_size > line2_size)

{

customers++;

temp.set(cycle);

line2.enqueue(temp);

line2_size++;

}

else

{

customers++;

temp.set(cycle);

line1.enqueue(temp);

line1_size++;

}

if (wait_time1 <= 0 && !line1.isempty())

{

line1.dequeue(temp);

line1_size--;

wait_time1 = temp.ptime();

line_wait += (cycle - temp.when());

served++;

}

if (wait_time2 <=0 && !line2.isempty())

{

line2.dequeue(temp);

line2_size--;

wait_time2 = temp.ptime();

line_wait += (cycle - temp.when());

served++;

}

if (wait_time1 > 0)

{

wait_time1--;

}

if (wait_time2 > 0)

{

wait_time2--;

}

sum_line += line1.queuecount();

sum_line += line2.queuecount();

}

if (customers > 0)

{

cout << "customers accepted: " << customers << endl;

cout << " customers served: " << served << endl;

cout << " turnaways: " << turnaways << endl;

cout << "average queue size: ";

cout.precision(2);

cout.setf(ios_base::fixed, ios_base::floatfield);

cout << (double)sum_line / cyclelimit << endl;

avg_wait_time = (double)line_wait / served;

cout << " average wait time: "

<< avg_wait_time << " minutes\n" << endl;;

}

else

cout << "No customers!\n" << endl;

// 平均等待时间不一定刚好是1，设置在一个区间内

} while ((perhour++) && (avg_wait_time < 0.9) || (avg_wait_time > 1.1));

cout << "When perhour = " << perhour << " , the average wait time"

" will be about 1 minute\n" << endl;

cout << "Done!\n";

return;

}

int main(int argc, char **argv)

{

p12_6();

while (cin.get());

}

// Queue.h

#pragma once

class Customer

{

private:

long arrive;

int processtime;

public:

Customer() { arrive = processtime = 0; }

void set(long when);

long when() const { return arrive; }

int ptime() const { return processtime; }

};

typedef Customer cItem;

class Queue

{

private:

struct Node { cItem item; struct Node * next; };

enum {Q_SIZE = 10};

Node * front;

Node * rear;

int items;

const int qsize;

Queue(const Queue & q) : qsize(0) {}

Queue & operator=(const Queue & q) { return *this; }

public:

Queue(int qs = Q_SIZE);

~Queue();

bool isempty() const;

bool isfull() const;

int queuecount() const;

bool enqueue(const cItem & item);

bool dequeue(cItem & item);

};

// Queue.cpp

#include "Queue.h"

#include <cstdlib>

Queue::Queue(int qs) : qsize(qs)

{

front = rear = NULL;

items = 0;

}

Queue::~Queue()

{

Node * temp;

while (front != NULL)

{

temp = front;

front = front->next;

delete temp;

}

bool Queue::isempty() const

{

return items == 0;

}

bool Queue::isfull() const

{

return items == qsize;

}

int Queue::queuecount() const

{

return items;

}

bool Queue::enqueue(const cItem & item)

{

if (isfull())

{

return false;

}

Node * add = new Node;

add->item = item;

add->next = NULL;

items++;

if (front == NULL)

{

front = add;

}

else

rear->next = add;

rear = add;

return true;

}

bool Queue::dequeue(cItem & item)

{

if (front == NULL)

{

return false;

}

item = front->item;

items--;

Node * temp = front;

front = front->next;

delete temp;

if (items == 0)

{

rear = NULL;

}

return true;

}

void Customer::set(long when)

{

processtime = std::rand() % 3 + 1;

arrive = when;

}

// Stack.h

#pragma once

typedef unsigned long Item;

class Stack

{

private:

enum {MAX = 10};

Item * pitems;

int size;

int top;

public:

Stack(int n = MAX);

Stack(const Stack & st);

~Stack();

bool isempty() const;

bool isfull() const;

bool push(const Item & item);

bool pop(Item & item);

Stack & operator=(const Stack & st);

};

// Stack.cpp

#include "Stack.h"

#include <iostream>

Stack::Stack(int n)

{

pitems = new Item[n];

size = n;

top = 0;

}

Stack::Stack(const Stack & st)

{

size = st.size;

pitems = new Item[size];

top = st.top;

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

{

pitems[i] = st.pitems[i];

}

Stack::~Stack()

{

delete[] pitems;

pitems = nullptr;

}

bool Stack::isempty() const

{

return top == 0;

}

bool Stack::isfull() const

{

return top == size;

}

bool Stack::push(const Item & item)

{

if (isfull())

{

return false;

}

pitems[top++] = item;

return true;

}

bool Stack::pop(Item & item)

{

if (isempty())

{

return false;

}

item = pitems[--top];

return true;

}

Stack & Stack::operator=(const Stack & st)

{

size = st.size;

pitems = new Item[size];

top = st.top;

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

{

pitems[i] = st.pitems[i];

}

return *this;

}

// Stock.h

#pragma once

#include <iostream>

class Stock

{

private:

char * company;

int shares;

double share_val;

double total_val;

void set_tot() { total_val = shares * share_val; }

public:

Stock();

Stock(const char * co, long n = 0, double pr = 0.0);

~Stock();

void buy(long num, double price);

void sell(long num, double price);

void update(double price);

void show() const;

friend std::ostream & operator<<(std::ostream & os, const Stock & st);

const Stock & topval(const Stock & s) const;

};

// Stock.cpp

#include "Stock.h"

#include <cstring>

Stock::Stock()

{

int len = std::strlen("no name");

company = new char[len + 1];

std::strcpy(company, "no name");

company[len] = '\0';

shares = 0;

share_val = 0.0;

total_val = 0.0;

}

Stock::Stock(const char * co, long n, double pr)

{

int len = std::strlen(co);

company = new char[len + 1];

std::strcpy(company, co);

if (n < 0)

{

std::cout << "Number of shares can't be negative; "

<< company << " shares set to n.\n";

shares = 0;

}

else

shares = n;

share_val = pr;

set_tot();

}

Stock::~Stock()

{

delete[] company;

company = nullptr;

}

void Stock::buy(long num, double price)

{

if (num < 0)

{

std::cout << "Number of shares purchased can't be negative. "

<< "Transaction is aborted.\n";

}

else

{

shares += num;

share_val = price;

set_tot();

}

void Stock::sell(long num, double price)

{

using std::cout;

if (num < 0)

{

cout << "Number of shares sold can't be negative. "

<< "Transaction is aborted.\n";

}

else if (num > shares)

{

cout << "You can't sell more than you have! "

<< "Transaction is aborted.\n";

}

else

{

shares -= num;

share_val = price;

set_tot();

}

void Stock::update(double price)

{

share_val = price;

set_tot();

}

void Stock::show() const

{

using std::cout;

using std::ios_base;

ios_base::fmtflags orig =

cout.setf(ios_base::fixed, ios_base::floatfield);

std::streamsize prec = cout.precision(3);

cout << "Company: " << company

<< " Shares: " << shares << '\n';

cout << "Share Price: $" << share_val;

cout.precision(2);

cout << " Total Worth: $" << total_val << '\n';

cout.setf(orig, ios_base::floatfield);

cout.precision(prec);

}

std::ostream & operator<<(std::ostream & os, const Stock & st)

{

using std::ios_base;

ios_base::fmtflags orig =

os.setf(ios_base::fixed, ios_base::floatfield);

std::streamsize prec = os.precision(3);

os << "Company: " << st.company

<< " Shares: " << st.shares << '\n';

os << " Share Price: $" << st.share_val;

os.precision(2);

os << " Total Worth: $" << st.total_val << '\n';

os.setf(orig, ios_base::floatfield);

os.precision(prec);

return os;

}

const Stock & Stock::topval(const Stock & s) const

{

if (s.total_val > total_val)

{

return s;

}

else

return *this;

}

// string2.h

#pragma once

#ifndef STRING2_H_

#define STRING2_H_

#include <iostream>

using std::ostream;

using std::istream;

class String2

{

private:

char * str;

int len;

static int num_strings;

static const int CINLIM = 80;

public:

String2(const char * s);

String2();

String2(const String2 &);

~String2();

int length() const { return len; }

String2 & operator=(const String2 &);

String2 & operator=(const char *);

char & operator[](int i);

const char & operator[](int i) const;

friend bool operator<(const String2 &st, const String2 &st2);

friend bool operator>(const String2 &st, const String2 &st2);

friend bool operator==(const String2 &st, const String2 &st2);

friend ostream & operator<<(ostream & os, const String2 &st);

friend istream & operator>>(istream & is, String2 &st);

static int HowMany();

String2 operator+(const String2 &) const;

String2 operator+(const char *) const;

friend String2 operator+(const char *, const String2 &);

void Stringlow();

void Stringup();

int has(char);

};

#endif // !STRING2_H_

// string2.cpp

#include <cstring>

#include "string2.h"

using std::cin;

using std::cout;

int String2::num_strings = 0;

int String2::HowMany()

{

return num_strings;

}

String2::String2(const char * s)

{

len = std::strlen(s);

str = new char[len + 1];

std::strcpy(str, s);

num_strings++;

}

String2::String2()

{

len = 4;

str = new char[1];

str[0] = '\0';

num_strings++;

}

String2::String2(const String2 & st)

{

num_strings++;

len = st.len;

str = new char[len + 1];

std::strcpy(str, st.str);

}

String2::~String2()

{

--num_strings;

delete[] str;

}

String2 & String2::operator=(const String2 & st)

{

if (this == &st)

{

return *this;

}

delete[] str;

len = st.len;

str = new char[len + 1];

std::strcpy(str, st.str);

return *this;

}

String2 & String2::operator=(const char * s)

{

delete[] str;

len = std::strlen(s);

str = new char[len + 1];

std::strcpy(str, s);

return *this;

}

char & String2::operator[](int i)

{

return str[i];

}

const char & String2::operator[](int i) const

{

return str[i];

}

bool operator<(const String2 & st, const String2 & st2)

{

return(std::strcmp(st.str, st2.str) < 0);

}

bool operator>(const String2 & st, const String2 & st2)

{

return(std::strcmp(st.str, st2.str) > 0);

}

bool operator==(const String2 & st, const String2 & st2)

{

return(std::strcmp(st.str, st2.str) == 0);

}

ostream & operator<<(ostream & os, const String2 & st)

{

os << st.str;

return os;

}

istream & operator>>(istream & is, String2 & st)

{

char temp[String2::CINLIM];

is.get(temp, String2::CINLIM);

if (is)

{

st = temp;

}

while (is && is.get() != '\n')

{

continue;

}

return is;

}

String2 String2::operator+(const String2 & st) const

{

int total_len = len + st.len;

char *temp = new char[total_len + 1];

std::strcpy(temp, str);

std::strcpy(temp + len, st.str);

temp[total_len] = '\0';

return String2(temp);

}

String2 String2::operator+(const char * s) const

{

int total_len = len + strlen(s);

char *temp = new char[total_len + 1];

std::strcpy(temp, str);

std::strcpy(temp + len, s);

temp[total_len] = '\0';

return String2(temp);

}

String2 operator+(const char * s, const String2 & st)

{

return String2(s) + st;

}

void String2::Stringlow()

{

for (int i = 0; i < len + 1; i++)

{

str[i] = tolower(str[i]);

}

void String2::Stringup()

{

for (int i = 0; i < len + 1; i++)

{

str[i] = toupper(str[i]);

}

int String2::has(char c)

{

int same = 0;

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

{

if (str[i] == c)

{

same++;

}

return same;

}

此文文博主原创文章，转载请注明出处

Jimmy's Blog

Jimmy Chen

C++ Primer Plus 第六版第十二章课后编程练习答案

赞过：

相关

本作品采用知识共享署名-相同方式共享 4.0 国际许可协议进行许可

发表回复取消回复

Jimmy Chen

赞过：

相关

本作品采用 知识共享署名-相同方式共享 4.0 国际许可协议 进行许可

发表回复 取消回复

本作品采用知识共享署名-相同方式共享 4.0 国际许可协议进行许可

发表回复取消回复