程序清单10.1+10.2+10.3
头文件stock00.h
1 //stock00.h
2 #ifndef STOCK00_H_ //如果没有定义STOCK00_H_
3 #define STOCK00_H_ //那么就定义STOCK00_H_
4
5 #include<string>
6 using namespace std;
7
8 class Stock //类声明
9 {
10 private:
11 string company;
12 long shares;
13 double share_val;
14 double total_val;
15 void set_tot();
16 public:
17 void acquire(const string &co, long n, double pr);
18 void buy(long num, double price);
19 void sell(long num, double price);
20 void update(double price);
21 void show();
22 };
23
24 inline void Stock::set_tot() //内联函数 或者按书上那种写法，两种一样
25 {
26 total_val = shares*share_val;
27 }
28
29 #endif // !STOCK00_H_ 结束预定义
stock00.cpp
1 #include<iostream>
2 #include"stock00.h"
3 using namespace std;
4
5 void Stock::acquire(const string &co, long n, double pr)
6 {
7 company = co;
8 if (n < 0)
9 {
10 cout << "shares can't be negative." << company << " shares set to 0.\n";
11 shares = 0;
12 }
13 else
14 shares = n;
15 share_val = pr;
16 set_tot();
17 }
18 void Stock::buy(long num, double price)
19 {
20 if (num < 0)
21 cout << "shares purchased can't be negative.\n";
22 else
23 {
24 shares += num;
25 share_val = price;
26 set_tot();
27 }
28 }
29 void Stock::sell(long num, double price)
30 {
31 if (num < 0)
32 cout << "shares sold can't be negative.\n";
33 else if (num > shares)
34 cout << "you can't sell more than you have.\n";
35 else
36 {
37 shares -= num;
38 share_val = price;
39 set_tot();
40 }
41 }
42 void Stock::update(double price)
43 {
44 share_val = price;
45 set_tot();
46 }
47 void Stock::show()
48 {
49 cout << "Company: " << company
50 << " Shares: " << shares << "\n"
51 << " Share Price: $ " << share_val
52 << " Tptal Worth: & " << total_val << "\n";
53 }
usestock0.cpp
1 #include<iostream>
2 #include"stock00.h"
3 using namespace std;
4
5 int main()
6 {
7 Stock cat;
8 cat.acquire("NanoSmart", 20, 12.50);
9 cat.show();
10 cat.buy(15, 18.125);
11 cat.show();
12 cat.sell(400, 20.0);
13 cat.show();
14 cat.buy(300000, 40.125);
15 cat.show();
16 cat.sell(300000, 0.125);
17 cat.show();
18
19 system("pause");
20 return 0;
21 }
修改stock.cpp文件中的show方法，使其数字格式统一
1 void Stock::show()
2 {
3 //将原始格式存入orig，设置cout对象的一个标记
4 //ios_base::fixed命令cout使用定点表示法，ios_base::floatfield设置输出时按浮点格式，小数点后有6位数
5 ios_base::fmtflags orig = cout.setf(ios_base::fixed, ios_base::floatfield);
6 //streamsize可以设置输入流的位数
7 //cout使用定点表示法时，显示三位小数
8 //保存当前流的位数到prec中
9 std::streamsize prec = cout.precision(3);
10
11 cout << "Company: " << company
12 << ", Shares:" << shares
13 << "\nShare Price: $" << share_val;
14 cout.precision(2);
15 cout << ", Total Worth: $" << total_val << '\n';
16
17 //返回调用show()之前的格式
18 cout.setf(orig, ios_base::floatfield);
19 cout.precision(prec);
20 }
构造函数和析构函数
程序清单10.4+10.5+10.6
头文件stock10.h
1 //stock10.h
2 #ifndef STOCK00_H_ //如果没有定义STOCK00_H_
3 #define STOCK00_H_ //那么就定义STOCK00_H_
4
5 #include<string>
6 using namespace std;
7
8 class Stock //类声明
9 {
10 private:
11 string company;
12 long shares;
13 double share_val;
14 double total_val;
15 void set_tot();
16 public:
17 Stock(); //默认构造函数
18 Stock(const string &co, long n = 0, double pr = 0.0); //构造函数，和前面例子中的acquire()相同，区别在于，程序声明对象时，将自动调用构造函数
19 ~Stock(); //析构函数
20 void buy(long num, double price);
21 void sell(long num, double price);
22 void update(double price);
23 void show();
24 };
25
26 inline void Stock::set_tot() //内联函数 或者按书上那种写法，两种一样
27 {
28 total_val = shares*share_val;
29 }
30
31 #endif // !STOCK00_H_ 结束预定义
函数定义stock10.cpp
1 #include<iostream>
2 #include"stock10.h"
3 using namespace std;
4
5 //默认构造函数
6 Stock::Stock()
7 {
8 cout << "Default constructor called\n";
9 company = "no name";
10 shares = 0;
11 share_val = 0.0;
12 total_val = 0.0;
13 }
14
15 //构造函数
16 Stock::Stock(const string &co, long n, double pr)
17 {
18 cout << "Constructor using " << co << " called\n";
19 company = co;
20 if (n < 0)
21 {
22 cout << "shares can't be negative." << company << " shares set to 0.\n";
23 shares = 0;
24 }
25 else
26 shares = n;
27 share_val = pr;
28 set_tot();
29 }
30
31 //析构函数
32 Stock::~Stock()
33 {
34 cout << "Bye, " << company << "!\n";
35 }
36
37 //其他方法
38 void Stock::buy(long num, double price)
39 {
40 if (num < 0)
41 cout << "shares purchased can't be negative.\n";
42 else
43 {
44 shares += num;
45 share_val = price;
46 set_tot();
47 }
48 }
49
50 void Stock::sell(long num, double price)
51 {
52 if (num < 0)
53 cout << "shares sold can't be negative.\n";
54 else if (num > shares)
55 cout << "you can't sell more than you have.\n";
56 else
57 {
58 shares -= num;
59 share_val = price;
60 set_tot();
61 }
62 }
63 void Stock::update(double price)
64 {
65 share_val = price;
66 set_tot();
67 }
68 void Stock::show()
69 {
70 //将原始格式存入orig，设置cout对象的一个标记
71 //ios_base::fixed命令cout使用定点表示法，ios_base::floatfield设置输出时按浮点格式，小数点后有6位数
72 ios_base::fmtflags orig = cout.setf(ios_base::fixed, ios_base::floatfield);
73 //streamsize可以设置输入流的位数
74 //cout使用定点表示法时，显示三位小数
75 //保存当前流的位数到prec中
76 std::streamsize prec = cout.precision(3);
77
78 cout << "Company: " << company
79 << ", Shares:" << shares
80 << "\nShare Price: $" << share_val;
81 cout.precision(2);
82 cout << ", Total Worth: $" << total_val << '\n';
83
84 //返回调用show()之前的格式
85 cout.setf(orig, ios_base::floatfield);
86 cout.precision(prec);
87 }
主函数usestock1.cpp
1 #include<iostream>
2 #include"stock10.h"
3 using namespace std;
4
5 int main()
6 {
7 //大括号的作用：stock1和stock2等自动变量将在程序退出其定义所属代码块时消失
8 //如果没有大括号，代码块将为整个main()，因此main()执行完，到达返回语句之后，才会调用析构函数，会看不到最后两条消息。
9 {
10 cout << "Using constructors to create new objects\n";
11 Stock stock1("NanoSmart", 12, 20.0); //隐式调用构造函数
12 stock1.show();
13 Stock stock2 = Stock("Boffo Objects", 2, 2.0); //显式调用构造函数
14 stock2.show();
15
16 cout << "Assigning stock1 to stock2!!!\n"; //将stock1分配给stock2!!！
17 stock2 = stock1;
18 cout << "Listing stock1 and stock2:\n";
19 stock1.show();
20 stock2.show();
21
22 cout << "Using a constructor to reset an object!!!\n"; //用构造函数重置对象
23 stock1 = Stock("Nifty Foods", 10, 50.0);
24 cout << "Revised stock1:\n"; //修订stock1
25 stock1.show();
26 cout << "Done\n";
27 }
28 system("pause");
29 return 0;
30 }
程序清单10.7+10.8+10.9（this指针+对象数组）
红色标记为相较于上一个例子新增的东西
头文件stock20.h
1 //stock20.h
2 #ifndef STOCK00_H_ //如果没有定义STOCK00_H_
3 #define STOCK00_H_ //那么就定义STOCK00_H_
4
5 #include<string>
6 using namespace std;
7
8 class Stock //类声明
9 {
10 private:
11 string company;
12 long shares;
13 double share_val;
14 double total_val;
15 void set_tot();
16 public:
17 Stock(); //默认构造函数
18 Stock(const string &co, long n = 0, double pr = 0.0); //构造函数，和前面例子中的acquire()相同，区别在于，程序声明对象时，将自动调用构造函数
19 ~Stock(); //析构函数
20 void buy(long num, double price);
21 void sell(long num, double price);
22 void update(double price);
23 //show()要加const，后面top要调用show(),是隐式访问的对象，所以类型要一致
24 void show()const;
25 //新增
26 const Stock & topval(const Stock & s)const;
27 };
28
29 inline void Stock::set_tot() //内联函数 或者按书上那种写法，两种一样
30 {
31 total_val = shares*share_val;
32 }
33
34 #endif // !STOCK00_H_ 结束预定义
函数定义stock20.cpp
1 #include<iostream>
2 #include"stock20.h"
3 using namespace std;
4
5 //默认构造函数
6 Stock::Stock()
7 {
8 company = "no name";
9 shares = 0;
10 share_val = 0.0;
11 total_val = 0.0;
12 }
13
14 //构造函数
15 Stock::Stock(const string &co, long n, double pr)
16 {
17 //cout << "Constructor using " << co << " called\n";
18 company = co;
19 if (n < 0)
20 {
21 cout << "shares can't be negative." << company << " shares set to 0.\n";
22 shares = 0;
23 }
24 else
25 shares = n;
26 share_val = pr;
27 set_tot();
28 }
29
30 //析构函数
31 Stock::~Stock()
32 {
33 }
34
35 //其他方法
36 void Stock::buy(long num, double price)
37 {
38 if (num < 0)
39 cout << "shares purchased can't be negative.\n";
40 else
41 {
42 shares += num;
43 share_val = price;
44 set_tot();
45 }
46 }
47
48 void Stock::sell(long num, double price)
49 {
50 if (num < 0)
51 cout << "shares sold can't be negative.\n";
52 else if (num > shares)
53 cout << "you can't sell more than you have.\n";
54 else
55 {
56 shares -= num;
57 share_val = price;
58 set_tot();
59 }
60 }
61 void Stock::update(double price)
62 {
63 share_val = price;
64 set_tot();
65 }
66 void Stock::show()const
67 {
68 //将原始格式存入orig，设置cout对象的一个标记
69 //ios_base::fixed命令cout使用定点表示法，ios_base::floatfield设置输出时按浮点格式，小数点后有6位数
70 ios_base::fmtflags orig = cout.setf(ios_base::fixed, ios_base::floatfield);
71 //streamsize可以设置输入流的位数
72 //cout使用定点表示法时，显示三位小数
73 //保存当前流的位数到prec中
74 std::streamsize prec = cout.precision(3);
75
76 cout << "Company: " << company
77 << ", Shares:" << shares
78 << "\nShare Price: $" << share_val;
79 cout.precision(2);
80 cout << ", Total Worth: $" << total_val << '\n';
81
82 //返回调用show()之前的格式
83 cout.setf(orig, ios_base::floatfield);
84 cout.precision(prec);
85 }
86
87 //新增
88 const Stock & Stock::topval(const Stock & s)const
89 {
90 if (s.total_val > total_val)
91 return s;
92 else
93 return *this;
94 }
主函数usestock2.cpp （都改了，添加了对象数组）
1 #include<iostream>
2 #include"stock10.h"
3 using namespace std;
4
5 const int STKS = 4;
6
7 int main()
8 {
9 //创建一个初始化对象数组
10 Stock stocks[STKS] =
11 {
12 Stock("NS",12,20.0),
13 Stock("B O",200,2.0),
14 Stock("M O",130,3.25),
15 Stock("F E",60,6.5)
16 };
17 cout << "Stock holding: " << endl;
18 int st;
19 for (st = 0; st < STKS; st++)
20 {
21 stocks[st].show();
22 }
23 //让top指针指向第一个元素
24 const Stock *top = &stocks[0];
25 //topval()每次只检查两个对象，所以程序使用for循环来检查整个数组
26 for (st = 1; st < STKS; st++)
27 {
28 top =&top -> topval(stocks[st]); //->的优先级高于&，所以可以看成top = & (top -> topval(stocks[st]));
29 //先用top调用topval(),将返回的对象的地址赋给top
30 }
31 cout << "\nmost valuable holding : \n";
32 top->show();
33
34 system("pause");
35 return 0;
36 }
程序清单10.10+10.11+10.12
头文件stack.h
//stack.h
#ifndef STACK_H_ //如果没有定义SSTACK_H_
#define STACK_H_ //那么就定义STACK_H_
typedef unsigned long Item;
class Stack //类声明
{
private:
enum { MAX = 10 };
Item items[MAX];
int top;
public:
Stack(); //默认构造函数
bool isempty() const;
bool isfull() const;
bool push(const Item & item);//压栈
bool pop(Item & item);//出栈
};
#endif // !STOCK00_H_ 结束预定义
函数定义stack.cpp
1 #include "stack.h"
2
3 //构造函数
4 Stack::Stack() //创建一个空栈
5 {
6 top = 0;
7 }
8
9 bool Stack::isempty() const
10 {
11 return top == 0;//top为0返回true，反之为false
12 }
13 bool Stack::isfull() const
14 {
15 return top == MAX;
16 }
17 bool Stack::push(const Item &item)
18 {
19 if (top<MAX)
20 {
21 items[top++] = item;
22 return true;
23 }
24 else
25 return false;
26 }
27 bool Stack::pop(Item &item)
28 {
29 if (top>0)
30 {
31 item = items[--top];
32 return true;
33 }
34 else
35 return false;
36 }
主函数stacker.cpp
1 #include<iostream>
2 #include<cctype>
3 #include "stack.h"
4 using namespace std;
5
6 void main()
7 {
8 Stack st;
9 char ch;
10 unsigned long po;
11 cout << "Enter A to add a purchase order, P to process a PO, Q to quit.\n";
12 while (cin >> ch&&toupper(ch) != 'Q')
13 {
14 while (cin.get() != '\n')//如果不是换行就继续
15 continue;
16 if (!isalpha(ch))//如果不是字母就继续
17 {
18 cout << '\a';
19 continue;
20 }
21 switch (ch)
22 {
23 case 'A':
24 case 'a':
25 cout << "Enter a PO number to add: ";
26 cin >> po;
27 if (st.isfull())//该方法判断：如果满了（top等于MAX）返回true，没满返回false
28 cout << "Stack already full\n";
29 else
30 st.push(po);
31 break;
32 case 'P':
33 case 'p':
34 if (st.isempty())
35 cout << "Stack already empty\n";
36 else
37 {
38 st.pop(po);
39 cout << "PO #" << po << " popped\n";
40 }
41 break;
42 }
43 cout << "Enter A to add a purchase order, P to process a PO, Q to quit.\n";
44 }
45 system("pause");
46 }