16.使用this指针复制数据.

头文件:

1 #include 
      
        2  3 using namespace std; 4  5 class Obj 6 { 7     int a, b; 8  9 public:10     Obj(int x = 0, int y = 0)11     {12         a = x;13         b = y;14     }15 16     void copy(Obj &);17     void display()18     {19         cout << "a = " << a << ", b = " << b << endl;20     }21 };22 23 void Obj::copy(Obj &aObj)24 {25     if (this == &aObj)26         return;27     this->a = aObj.a;28     this->b = aObj.b;29 }
      

源文件:

1 #include "obj.h" 2  3 void main(void) 4 { 5     Obj x1(22, 25), x2(33, 46); 6  7     cout << "x1: "; 8     x1.display(); 9     cout << "x2: ";10     x2.display();11     x1.copy(x2);12     cout << "x1: ";13     x1.display();14 }

结果:

x1: a = 22, b = 25

x2: a = 33, b = 46

x1: a = 33, b = 46

 

Mark:

　　当一个对象调用成员函数时,系统先将该对象的地址赋给this指针,然后调用成员函数,成员函数对成员数据进行操作时,隐含使用了this指针.

 

17.完整实现str类的例子.

头文件:

1 #ifndef _STR_H 2 #define _STR_H 3  4 #include 
      
        5 #include 
       
         6  7 using namespace std; 8  9 class str10 {11 private:12     char *st;13 14 public:15     str(char *s);16     str(str &s);17     str & operator = (str &a);18     str & operator = (char *s);19     void print()20     {21         cout << st << endl;22     }23 24     ~str()25     {26         delete st;27     }28 };29 30 str::str(char *s)31 {32     st = new char[strlen(s) + 1];33     strcpy(st, s);34 }35 36 str::str(str &a)37 {38     st = new char[strlen(a.st) + 1];39     strcpy(st, a.st);40 }41 42 str & str::operator = (str &a)43 {44     if (this == &a)45         return *this;46     delete st;47     st = new char[strlen(a.st) + 1];48     strcpy(st, a.st);49     return *this;50 }51 52 str & str::operator = (char *s)53 {54     delete st;55     st = new char[strlen(s) + 1];56     strcpy(st, s);57     return *this;58 }59 60 #endif
       
      

源文件:

1 #include "str.h" 2  3 void main(void) 4 { 5     str s1("We"), s2("They"), s3(s1); 6  7     s1.print(); 8     s2.print(); 9     s3.print();10 11     s2 = s1 = s3;12     s3 = "Go home!";13     s3 = s3;14     s1.print();15     s2.print();16     s3.print();17 }

结果:

We

They

We

We

We

Go home!

 

18.求4个数的最大值的类模板程序.

头文件:

1 #ifndef _MAX4_H 2 #define _MAX4_H 3  4 #include 
      
        5  6 using namespace std; 7  8 template 
       
         9 class Max410 {11     T a, b, c, d;12     T Max(T a, T b)13     {14         return (a > b) ? a : b;15     }16 17 public:18     Max4(T, T, T, T);19     T Max(void);20 };21 22 template 
        
         23 Max4
         
          ::Max4(T x1, T x2, T x3, T x4):a(x1),b(x2),c(x3),d(x4) 24 {25 }26 27 template 
          
           28 T Max4
           
            ::Max(void)29 {30 return Max(Max(a, b), Max(c, d));31 }32 33 #endif
           
          
         
        
       
      

源文件:

1 #include "max4.h"2 3 void main(void)4 {5     Max4
      
        C('W', 'w', 'a', 'A');6     Max4
       
         A(-25, -67, -66, -256);7     Max4
        
          B(1.25, 4.3, -8.6, 3.5);8     cout << C.Max() << " " << A.Max() << " " << B.Max() << endl;9 }
        
       
      

结果:

w -25 4.3

 

19.演示对4个数字求和的类模板程序.

头文件:

1 #ifndef _SUM_H 2 #define _SUM_H 3  4 template 
      
        5 class Sum 6 { 7 private: 8     T m[size]; 9 10 public:11     Sum(T a, T b, T c, T d)12     {13         m[0] = a;14         m[1] = b;15         m[2] = c;16         m[3] = d;17     }18 19     T S()20     {21         return m[0] + m[1] + m[2] + m[3];22     }23 };24 25 #endif
      

源文件:

1 #include 
      
        2 #include "sum.h" 3  4 using namespace std; 5  6 void main(void) 7 { 8     Sum
       
         num1(-23, 5, 8, -2); 9     Sum
        
          f1(3.5f, -8.5f, 8.8f, 9.7f);10     Sum
         
           d1(355.4, 253.8, 456.7, -67.8);11     Sum
          
            c1('W', -2, -1, -1);            //字符减,等效于'W','U','T','S'12     cout << num1.S() << ", " << f1.S() << ", " << d1.S() << ", " << c1.S() << endl;13 }
          
         
        
       
      

结果:

-12, 13.5, 998.1, S

 

20.使用缺省内联函数实现单一继承

头文件:

1 #include 
      
        2  3 using namespace std; 4  5 class Point 6 { 7 private: 8     int X, Y; 9 10 public:11     Point(int a, int b)12     {13         X = a;14         Y = b;15         cout << "Point..." << endl;16     }17 18     void Showxy()19     {20         cout << "X = " << X << ", Y = " << Y << endl;21     }22 23     ~Point()24     {25         cout << "Delete Point" << endl;26     }27 };28 29 class Rectangle:public Point30 {31 private:32     int H, W;33 34 public:35     Rectangle(int a, int b, int h, int w):Point(a, b)36     {37         H = h;38         W = w;39         cout << "Rectangle..." << endl;40     }41 42     void Show()43     {44         cout << "H = " << H << ", W = " << W << endl;45     }46 47     ~Rectangle()48     {49         cout << "Delete Rectangle" << endl;50     }51 };
      

源文件:

1 #include "rectangle.h"2 3 void main(void)4 {5     Rectangle r1(3, 4, 5, 6);6     r1.Showxy();7     r1.Show();8 }

结果:

Point...

Rectangle...

X = 3, Y = 4

H = 5, W = 6

Delete Rectangle

Delete Point

 

Mark:

　　当定义派生类的一个对象时,首先调用基类的构造函数,对基类成员进行初始化,然后执行派生类的构造函数,如果某个基类仍是一个派生类,则这个过程递归进行.