//复数类，构造函数和重载+运算符#include 
     
      #include 
      
       using namespace std;class Complex{public:    Complex(double r,double i=0){//缺省参数i        real=r;        image =i;    }    void Show(){        cout<
       
        0)cout<<"+"<
        <<"i"<
       
      
     

//定义一个抽象类Shape，它有一个纯虚函数GetPerimeter()；派生出四边型类Rectangle和圆类Circle，在派生类中重载函数GetPerimeter()，用于求图形的周长，编写测试程序进行测试。#include 
     
      #include 
      
       using namespace std;class Shape{public:    virtual double GetPPerimeter() const=0;};class Rectangle:public Shape {    Rectangle(double w, double h)  {   width = w;   height = h;  }    double GetPPerimeter()const{        return 2*(width+height);    }private:    double width, height; };class Circle:public Shape {  public:      Circle(double r)  {   radius = r;  }       double GetPerimeter() const  {           return 3.1415926 * radius * 2;  }  private:      double radius; };
      
     

 如果一个运算符函数是成员函数，则它的第一个（左侧）运算对象绑定到隐式的this指针上，所以成员运算符函数的（显式）参数数量比运算符的运算对象少一个。即一个参数有两个运算对象。

IO运算符一般被声明为友元。

//设计一个日期类Date,，要求：  （1）包含年(year)、月(month)和日(day)私有数据成员。  （2）包含构造函数，重载输出运算符“<<”与重载输入运算符“>>”。#include 
     
      #include 
      
       using namespace std;class Date{private:    int year;    int month;    int day;    void SetYear(int y) { year = y; }        void SetMonth(int m) { month = m; }      void SetDay(int d) { day = d; }        int GetYear() const { return year; }        int GetMonth() const { return month; }      int GetDay() const { return day; } public:    friend istream &operator>>(istream &in,Date &dt);    friend ostream &operator<<(ostream &out, const Date &dt);    Date(int y=2010,int m=1,int d=1):year(y),month(m),day(d){};    };istream &operator>>(istream &in,Date &dt){        int y,m,d;        cout<<"输入年：";        in>>y;        cout<<"输入月：";        in>>m;        cout<<"输入日:";        in>>d;        dt.SetYear(y);        dt.SetMonth(m);        dt.SetDay(d);         return in;    }    ostream &operator<<(ostream &out, const Date &dt)    {        out << dt.GetYear() << "年" << dt.GetMonth() << "月" << dt.GetDay() << "日";        return out;    }int main(){    Date d;    cin>>d;    cout<
       
        <
       
      
     

 

1 //虚继承解决菱形二义性 2 //定义Person（人）类，由Person分别派生出Teacher（教师）类和Cadre（干部）类，再由Teacher（教师）类和Cadre（干部）类采用多重继承方式派生出新类TeacherCadre（教师兼干部）类 3 #include 
     
       4 #include 
      
        5 using namespace std; 6 class Person {  7 protected:   8     char name[18];     9     int age;     10     char sex[3];      11 public:  Person(char nm[], int ag, char sx[])  12          {  13              strcpy(name, nm);    14              age = ag;      15              strcpy(sex, sx);  16          }       17          void Show() const    18          {    cout << "姓名:" << name << endl;   19          cout << "年龄:" << age << endl;    20          cout << "性别:" << sex << endl;    } 21 };  22 class Teacher: virtual public Person  23 {  protected:  24     char title[18]; 25 public:  26     Teacher(char nm[], int ag, char sx[], char tl[]): Person(nm, ag, sx)  { strcpy(title, tl); }  //t1是职称27     void Show() const     28     {    Person::Show();      29     cout << "职称:" << title << endl;   30     cout << endl;     } 31 };   32 class Cadre: virtual public Person 33 {  protected:  char post[18];  //职务  34 public:  Cadre(char nm[], int ag, char sx[], char pt[]): Person(nm, ag, sx)  { strcpy(post, pt); }35          void Show() const     36          {    Person::Show();      37          cout << "职务:" << post << endl;  38          cout << endl;     }  }; 39   class TeacherCadre: public Teacher, public Cadre { 40   protected:  double wages; //工资41   public:  42       TeacherCadre(char nm[], int ag, char sx[], char tl[], char pt[], double wg)    : Person(nm, ag, sx), Teacher(nm, ag, sx, tl), Cadre(nm, ag, sx, pt)  { wages = wg; }    43       void Show() const     {    44           Person::Show();     45           cout << "职称:" << title << endl;  46           cout << "职务:" << post << endl;   47           cout << "工资:" << wages << "元" << endl;  48           cout << endl;    }  };  49   int main()     {  50       Teacher objTeacher("文冠杰", 48, "男", "教授");  51       Cadre objCadre("周杰", 56, "男", "院长");  52       TeacherCadre objTeacherCadre("李靖", 50, "女", "教授", "院长", 6890);  53       objTeacher.Show();    54       objCadre.Show();      55       objTeacherCadre.Show();     56       return 0;               57   }
      
     

//虚析构函数//设计一个基类Shape，Shape中包含成员函数Show()，将Show()声明为纯虚函数。Shape类公有派生矩形类Rectangle和圆类Circle，分别定义Show()实现其主要几何元素的显示。使用抽象类Shape类型的指针，当它指向某个派生类的对象时，就可以通过它访问该对象的虚成员函数Show()，要求编写测试程序#include 
     
      #include 
      
       using namespace std;const double PI = 3.1415926;    class Shape {  public:          virtual ~Shape() { cout<<"1"<
       
        Show();           delete p;           p = new Rectangle(1, 2);        p->Show();           delete p;            return 0;                    }//输出结果：3 1 2 1
       
      
     

 

#include 
     
       using namespace std;   const double PI = 3.1415926;  class Shape {  public:  Shape() { }  ;             virtual ~Shape() { };  //抽象类         virtual void ShowArea() const = 0;             static double totalArea;            static void ShowTotalArea() { cout << "总面积:" << totalArea << endl; }};class Circle: public Shape { private:  double radius;     public:  Circle(double r): radius(r) { totalArea += PI * r * r; }          ~Circle() { }              virtual void ShowArea()  const { cout << "圆面积:" << PI * radius * radius << endl; };};class Rectangle: public Shape { private:  double length;   double width;    public:  Rectangle(double l, double w): length(l), width(w){ totalArea += l * w; }          ~Rectangle() { }           virtual void ShowArea() const { cout << "矩形面积:" << length * width << endl; }; };double Shape::totalArea=0; //静态数据成员的定义int main()  {     Circle c(1);         c.ShowArea();          Rectangle r(1, 2);     r.ShowArea();     Shape::ShowTotalArea();  //静态成员函数的调用    return 0;}
     

 

#include 
      
        using namespace std;   class Staff { protected:  int num;                  char name[18];                double rateOfAttend;                double basicSal;               double prize;            static int count;       public:  Staff(){ }             void Input()    {                num = ++count;                 cout << "请输入编号为" << num <<"号员工的信息" << endl;                cout << "姓名:";   cin >> name;                   cout << "基本工资:";               cin >> basicSal;                  cout << "奖金:";                cin >> prize;                  cout <<"出勤率(0~1):";                cin >> rateOfAttend;              }           void Output() const        {               cout << "编号:" << num << endl;     cout << "姓名:" << name << endl;                  cout << "基本工资:" << basicSal << "元" << endl;                 cout << "奖金:" << prize << "元" << endl;                  cout << "出勤率:" << rateOfAttend * 100 << "%" << endl;            }           void OutputWage() const    {                cout << "实发工资:"      << basicSal + prize * rateOfAttend << "元" << endl;           }};   int Staff::count = 1000;       class Saleman : public Staff {  protected:  float deductRate;                 float personAmount;     public:  Saleman (){ };              void Input()     {             Staff::Input();                   cout << "个人销售额:";   cin >> personAmount;                 cout << "提成比例:";   cin >> deductRate;            }           void Output() const     {                Staff::Output();                 cout << "个人销售额:" << personAmount << "元" << endl;                 cout << "提成比例:" << deductRate * 100 << "%" << endl;   }           void OutputWage() const    {                cout << "实发工资:"         << basicSal + prize * rateOfAttend    + personAmount * deductRate     << "元" << endl;      }};  class Manager: public Staff {  protected:  double totalDeductRate;                 double totalAmount;     public:  Manager(){ }                void Input()      {               Staff::Input();                    cout << "公司总销售额:";               cin >> totalAmount;                  cout << "提成比例:";                cin >> totalDeductRate;            }           void Output() const      {                Staff::Output();                  cout << "公司总销售额:" << totalAmount << "元" << endl;                 cout << "提成比例:" << totalDeductRate * 100 << "%" << endl;           }           void OutputWage() const{                cout << "实发工资:"         << basicSal + prize * rateOfAttend    + totalAmount * totalDeductRate     << "元" << endl;              } };   int main()         {      char flag = 'Y';            while (toupper(flag) == 'Y')  {   cout << "请选择录入类别(1.员工 2.销售员 3.经理)";      int n;   cin >> n;    if (n == 1)   { // 员工           Staff objStaff;               objStaff.Input();                objStaff.Output();                objStaff.OutputWage();        }   else if (n == 2)   {            Saleman objSaleman;                objSaleman.Input();                objSaleman.Output();                objSaleman.OutputWage();        }   else if (n == 3)   {            Manager objManager;               objManager.Input();               objManager.Output();                objManager.OutputWage();        }   else   {         cout << "选择有误!"<< endl;      }    cout << endl << "是否继续录入信息?(Y/N)";   cin >> flag;        }        return 0;  }