c++ Primer Plus（第六版）第十二章习题，写代码之路
c++ Primer Plus（习题12.1)
//12.1头文件
#pragma once
#ifndef COW_H
#define COW_H
#include
#include
class Cow
{
private:
char name[20];
char *hobby;
double weight;
public:
Cow();
Cow(const char* nm, const char *ho, double wt);
Cow(const Cow&c); //复制构造函数
~Cow();
Cow&operator=(const Cow&c);
void ShowCow()const;
};
#endif // !COW_H
#include"cow.h"
Cow::Cow()
{
name[0] = '\0';
hobby = new char[1];
hobby[0] = '\0'; //为了与后面析构函数的delete配套,nullptr为空指针新关键字
weight = 0.0;
}
Cow::Cow(const char* nm, const char *ho, double wt)
{
std::strcpy(name, nm);
hobby = new char[std::strlen(ho) + 1];
std::strcpy(hobby, ho);
weight = wt;
}
Cow::Cow(const Cow&c) //复制构造函数
{
std::strcpy(name, c.name);
hobby = new char[std::strlen(c.hobby) + 1];
std::strcpy(hobby, c.hobby);
weight = c.weight;
}
Cow::~Cow()
{
delete [] hobby;
}
Cow& Cow::operator=(const Cow&c)
{
if (this == &c)
return *this;
delete[] hobby; //删除指针再指向的内存
hobby = new char[std::strlen(c.hobby) + 1];
std::strcpy(name, c.name);
std::strcpy(hobby, c.hobby);
weight = c.weight;
return *this; //this为对象指针，值向调用对象
}
void Cow::ShowCow()const
{
std::cout << "Name: " << name << std::endl
<< "Hobby: " << hobby << std::endl
<< "Weight: " << weight << std::endl;
}c++ Primer Plus（习题12.2)
//自己的string 类，顺便做题目
#pragma once
#ifndef MYSTRING_H
#define MYSTRING_H
#include
using std::ostream;
using std::istream;
class String
{
private:
char *str;
int len;
static int num_strings; //静态类成员
static const int CINLIMN = 80; //字符串的最大值
public:
//构造函数和其它方法
String(const char*s);
String();
~String();
String(const String &s); //复制构造函数
int length()const { return len; }
//运算符重载
String operator+(const String&s)const; //合并
String operator+(const char*); //合并
String& operator=(const String&s);
String&operator=(const char*); //字符串赋值
char &operator[](int i); //重载[]运算符,给字符串某位置赋值
const char&operator[](int i)const;
String &stringlow(); //把字符串变成小写
String &stringup();
int has(char a); //记录字符出现次数
//友元函数
friend String operator+(char *st, const String&s); //重载一个字符串与string合并
friend bool operator<(const String&st, const String&st2);
friend bool operator>(const String&st, const String&st2);
friend bool operator==(const String&st, const String&st2);
friend ostream&operator<<(ostream&os, const String &st);
friend istream&operator >> (istream&is,String&st);
//静态成员函数，智能使用静态类成员
static int HowMaxny();
};
#endif // !MYSTRING_H
#include
#include
#include"mystring.h"
using std::cout;
using std::cin;
//初始化静态类成员
int String::num_strings = 0;
//静态类方法
int String::HowMaxny()
{
return num_strings;
}
//成员方法
String::String(const char*s)
{
len = strlen(s);
str = new char[len + 1];
std::strcpy(str, s);
num_strings++;
}
String::String()
{
len = 4;
str = new char[1];
str[0] = '\0';
num_strings++;
}
String::String(const String &s)
{
num_strings++;
len = s.len;
str = new char[len + 1];
std::strcpy(str, s.str);
}
String::~String()
{
--num_strings;
delete[] str;
}
//重载的运算符方法
//将string对象复制给string对象
String& String::operator=(const String&s)
{
if (this == &s)
return *this;
delete[]str;
len = s.len;
str = new char[len + 1];
std::strcpy(str, s.str);
return *this;
}
//将字符串复制给对象
String& String::operator=(const char*z)
{
delete[]str;
len = strlen(z);
str = new char[len + 1];
std::strcpy(str, z);
return *this;
}
//重载加号使字符串合并，与string合并
String String::operator+(const String&s)const
{
String temp;
temp.len = len + s.len;
delete[]temp.str;
temp.str = new char[temp.len + 1];
std::strcpy(temp.str, str);
std::strcat(temp.str, s.str);
return temp;
}
//与字符串合并，字符串在后面
String String::operator+(const char*s)
{
String temp;
temp.len = len + strlen(s);
delete[]temp.str;
temp.str = new char[temp.len+1];
std::strcpy(temp.str, str);
std::strcat(temp.str, s);
return temp;
}
//字符串在前面与string对象合并
String operator+(char *st, const String&s)
{
String temp;
temp.len = strlen(st) + s.len;
delete[]temp.str;
temp.str = new char[temp.len + 1];
std::strcpy(temp.str, st); //问题在这里，strcpy写成strcat
std::strcat(temp.str, s.str);
return temp;
}
//改写字符串中的某个字符
char &String::operator[](int i)
{
return str[i];
}
//只是读string中的某个字符
const char &String::operator[](int i)const
{
return str[i];
}
bool operator<(const String&st, const String&st2)
{
return (std::strcmp(st.str, st2.str)<0);
}
bool operator>(const String&st, const String&st2)
{
return st2 < st; //直接换简单粗暴
}
bool operator==(const String&st, const String&st2)
{
return (std::strcmp(st.str, st2.str)==0);
}
//把字符串全部变成小写
String &String::stringlow() //考虑要不要改变原字符串
{
int i = 0;
while (i> (istream&is, String&st)
{
char temp[String::CINLIMN];
is.get(temp, String::CINLIMN);
if (is)
st = temp;
while (is&&is.get() != '\n')
continue;
return is;
} //书上提供的测试
#include
using namespace std;
#include"mystring.h"
int main()
{
String s1(" and i am a C++ student.");
String s2 = "Please enter you name: ";
String s3;
cout << s2;
cin >> s3;
s2 = "My name is "+s3;
cout << s2 << ".\n";
s2 = s2 + s1;
s2.stringup();
cout << "The string\n" << s2 << "\ncontains " << s2.has('A')
<< " 'A' characters in it.\n";
s1 = "red";
String rgb[3] = { String(s1),String("green"),String("blue") };
cout << "Enter the name of primary color for mixing light: ";
String 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 0;
} c++ Primer Plus（习题12.3)
//stock.h
#ifndef STOCK_H_
#define STOCK_H_
#include
using namespace std;
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(const Stock &);
~Stock();
void buy(long num, double price);
void sell(long num, double price);
void update(double price);
const Stock & topval(const Stock & s)const;
Stock & operator=(const Stock & s);
friend ostream & operator<<(ostream & os, const Stock & s);
};
#endif #include
#include "stock.h"
Stock::Stock() {
company = new char[8];
strcpy(company, "no name");
shares = 0;
share_val = 0.0;
total_val = 0.0;
}
Stock::Stock(const char *co, long n, double pr) {
int len = strlen(co);
company = new char[len + 1];
strcpy(company, co);
if (n < 0)
{
cout << "Number of shares can't be negative; "
<< company << " shares set to 0.\n";
shares = 0;
}
else
shares = n;
share_val = pr;
set_tot();
}
Stock::Stock(const Stock & s) {
int len = strlen(s.company);
company = new char[len + 1];
strcpy(company, s.company);
shares = s.shares;
set_tot();
}
Stock::~Stock() {
delete[] company;
}
void Stock::buy(long num, double price) {
if (num < 0)
{
cout << "Number of shares purchased cannot be negative. " << "Transaction is aborted.\n";
}
else
{
shares += num;
share_val = price;
set_tot();
}
}
void Stock::sell(long num, double price) {
if (num < 0)
{
cout << "Number of shares sold cannot be negative. " << "Transaction is aborted.\n";
}
else if (num > shares) {
cout << "You cannot 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();
}
const Stock & Stock::topval(const Stock & s)const {
if (s.total_val > total_val)
return s;
else
return *this;
}
Stock & Stock::operator=(const Stock & s) {
int len = strlen(s.company);
company = new char[len + 1];
strcpy(company, s.company);
shares = s.shares;
set_tot();
return *this;
}
ostream & operator<<(ostream & os, const Stock & s) {
ios_base::fmtflags orig = cout.setf(ios_base::fixed, ios_base::floatfield);
streamsize prec = cout.precision(3);
cout << "Company: " << s.company << " Shares: " << s.shares << '\n';
cout << " Share Price: $" << s.share_val;
cout.precision(2);
cout << " Total Worth: $" << s.total_val << '\n';
cout.setf(orig, ios_base::floatfield);
cout.precision(prec);
return os;
} //又是熟悉的方法，注意new和delete的配合就行，书上大部分的源码
#include
#include "stock.h"
const int STKS = 4;
int main() {
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)
};
cout << "Stock holdings:\n";
int st;
for (st = 0; st < STKS; st++) {
cout << stocks[st];
}
const Stock* top = &stocks[0];
for (st = 1; st < STKS; st++) {
top = &top->topval(stocks[st]);
}
cout << "\nMost valuable holding:\n";
cout << *top;
cin.get();
return 0;
} c++ Primer Plus（习题12.4)
//stock.h
#ifndef STOCK_H_
#define STOCK_H_
#include
using namespace std;
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(const Stock &);
~Stock();
void buy(long num, double price);
void sell(long num, double price);
void update(double price);
const Stock & topval(const Stock & s)const;
Stock & operator=(const Stock & s);
friend ostream & operator<<(ostream & os, const Stock & s);
};
#endif #include
#include "stock.h"
Stock::Stock() {
company = new char[8];
strcpy(company, "no name");
shares = 0;
share_val = 0.0;
total_val = 0.0;
}
Stock::Stock(const char *co, long n, double pr) {
int len = strlen(co);
company = new char[len + 1];
strcpy(company, co);
if (n < 0)
{
cout << "Number of shares can't be negative; "
<< company << " shares set to 0.\n";
shares = 0;
}
else
shares = n;
share_val = pr;
set_tot();
}
Stock::Stock(const Stock & s) {
int len = strlen(s.company);
company = new char[len + 1];
strcpy(company, s.company);
shares = s.shares;
set_tot();
}
Stock::~Stock() {
delete[] company;
}
void Stock::buy(long num, double price) {
if (num < 0)
{
cout << "Number of shares purchased cannot be negative. " << "Transaction is aborted.\n";
}
else
{
shares += num;
share_val = price;
set_tot();
}
}
void Stock::sell(long num, double price) {
if (num < 0)
{
cout << "Number of shares sold cannot be negative. " << "Transaction is aborted.\n";
}
else if (num > shares) {
cout << "You cannot 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();
}
const Stock & Stock::topval(const Stock & s)const {
if (s.total_val > total_val)
return s;
else
return *this;
}
Stock & Stock::operator=(const Stock & s) {
int len = strlen(s.company);
company = new char[len + 1];
strcpy(company, s.company);
shares = s.shares;
set_tot();
return *this;
}
ostream & operator<<(ostream & os, const Stock & s) {
ios_base::fmtflags orig = cout.setf(ios_base::fixed, ios_base::floatfield);
streamsize prec = cout.precision(3);
cout << "Company: " << s.company << " Shares: " << s.shares << '\n';
cout << " Share Price: $" << s.share_val;
cout.precision(2);
cout << " Total Worth: $" << s.total_val << '\n';
cout.setf(orig, ios_base::floatfield);
cout.precision(prec);
return os;
} //书上的一个测试程序，觉得赋值运算符没体现出来，复制构造函数也没用。
#include
#include
#include"stack.h"
int main()
{
using namespace std;
char ch;
Stack st;
unsigned long po;
cout << "Please enter A to add a customer name and payment,\n"
<< "D to delete a customer,or Q to exit.\n";
while (cin >> ch&&toupper(ch) != 'Q')
{
while (cin.get() != '\n')
continue; //清空多余字符
if (!isalpha(ch))
{
cout << "\a"; //判断是否输入为字母
continue;
}
switch (ch)
{
case 'A':
case'a':
cout << "Enter a PO number to add: ";
cin >> po;
if (st.isfull())
cout << "stack is full!\n";
else
st.push(po);
break;
case'd':
case'D':
if (st.isempty())
cout << "stack already empty.\n";
else
{
st.pop(po);
cout << "PO # " << po << " been delete!\n";
}
break;
}
cout << "Please enter A to add a customer name and payment,\n"
<< "D to delete a customer,or Q to exit.\n";
}
cout << "Bye!\n";
return 0;
}
c++ Primer Plus（习题12.5)
//c++版，书上的源码
#pragma once
#pragma execution_character_set("utf-8")
//本文件为utf-8编码格式
#ifndef QUEUE_H_
#define QUEUE_H_
using namespace std;
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 Item;
class Queue
{
private:
struct Node { Item 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 Item &item);
bool dequeue(Item &item);
};
#endif #include"myqueue.h"
#include
Queue::Queue(int qs) :qsize(qs) {
front = rear = nullptr;
items = 0;
}
Queue::~Queue() {
Node *temp;
while (front != nullptr) {
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 Item &item) {
if (items == qsize)
return false;
Node *add = new Node;
add->item = item;
add->next = nullptr;
items++;
if (front == nullptr)
front = add;
else
rear->next = add;
rear = add;
return true;
}
bool Queue::dequeue(Item &item) {
if (items == 0)
return false;
item = front->item;
items--;
Node *temp = front;
front = front->next;
delete temp;
if (items == 0)
rear = nullptr;
return true;
}
void Customer::set(long when) {
processtime = std::rand() % 3 + 1;
arrive = when;
} //书上的源码，题目的意思是自己玩他设计的这个程序
//来模拟银行挣钱的秘诀，看懂了程序改一下简单，但本人没怎么改，增加了一个队列而已
//秘诀就是平均每小时来50个人，等候时间大于200；
#include
#include
#include
#include "myqueue.h"
const int MIN_PER_HR = 60;
bool newcustomer(double x);
int main()
{
srand(time(0));
cout << "Case Study: Bank of Heather Automatic Teller\n";
cout << "Enter maximum size of queue: "; //最大的排队人数
int qs;
cin >> qs;
Queue line1(qs);
Queue line2(qs);
cout << "Enter the number of simulation hours: "; //测试的时间
int hours;
cin >> hours;
long cyclelimit = MIN_PER_HR*hours;
cout << "Enter the average number of cunstomers per hour: "; //每小时的额客户数
double perhour;
cin >> perhour;
double min_per_cust;
min_per_cust = MIN_PER_HR / perhour; //记录总的分钟数
Item temp;
long turnaways = 0; //拒绝人数
long customers = 0; //来的人数
long served = 0; //服务人数
long sum_line = 0; //队列的长度
int wait_time1 = 0; //取款机空闲的等待时间
long wait_time2 = 0;
long line_wait = 0; //队列的总等待时间
for (long cycle = 0; cycle < cyclelimit; cycle++)
{
if (newcustomer(min_per_cust))
{
if (line1.isfull() && line2.isfull())
turnaways++;
else {
customers++;
temp.set(cycle);
if (line1.queuecount() < line2.queuecount())
line1.enqueue(temp);
else
line2.enqueue(temp);
}
}
if (wait_time1 <= 0 && !line1.isempty())
{
line1.dequeue(temp);
wait_time1 = temp.ptime();
line_wait += cycle - temp.when();
served++;
}
if (wait_time2 <= 0 && !line2.isempty())
{
line2.dequeue(temp);
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() + line2.queuecount()) / 2;
}
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;
cout << "average wait time: " << (double)line_wait / served << " minutes\n";
}
else
cout << "No customers!\n";
cout << "Done!\n";
return 0;
}
bool newcustomer(double x)
{
return (rand()*x / RAND_MAX < 1);
} 过年前清完，这个寒假才有意义············