目录

1. 派生类定义

2. 派生类的访问控制、构造、同名覆盖、多态性、虚函数、多继承、虚继承

3. 派生类对象的克隆

4. 典型范例——各类物体面积求和

5. 其他继承方式

5.1 私有继承和保护继承

class 派生类名:public 基类名
{
public:
    派生类公有函数成员
private:
    派生类私有函数成员
private:
    派生类私有数据成员
};

2. 派生类的访问控制、构造、同名覆盖、多态性、虚函数、多继承、虚继承

• protected访问控制专用于继承和派生，protected修饰的成员是保护成员

#include 
#include 
#include 
using namespace std;

class CPerson
{
public:
	CPerson(string Name, int Age) :m_Name(Name), m_Age(Age) {}
	void SetName(string Name)
	{
		m_Name = Name;
	}
	void SetAge(int Age)
	{
		m_Age = Age;
	}
	const string& GetName()const
	{
		return m_Name;
	}
	int GetAge()const
	{
		return m_Age;
	}
	void Show()const
	{
		cout << m_Name << ',' << m_Age << "years old. " << endl;
	}
protected:
	string m_Name;
	int m_Age;
};

class CStudent :public CPerson
{
public:
	CStudent(string Name, int Age) :CPerson(Name, Age) {}
	void Show()const;	//同名覆盖原则
	void StudyCourse(string strCourse);
	void ShowAllStudyCourse()const;
private:
	vector m_strVec;
};

void CStudent::Show()const
{
	CPerson::Show();
	cout << "A student" << endl;
}

void CStudent::StudyCourse(string strCourse)
{
	this->m_strVec.push_back(strCourse);
}

void CStudent::ShowAllStudyCourse()const
{
	cout << m_Name << "nStudent's draft courses list:" << endl;
	for (size_t i = 0; i < m_strVec.size(); i++)
	{
		cout << m_strVec[i] << endl;
	}
	cout << endl;
}

class CTeacher:virtual public CPerson	// virtual是虚继承,避免出现多义性问题
{
public:
	CTeacher(string Name, int Age) :CPerson(Name, Age) {}
	void Show()const;
	void TeacherCourse(string strCourse);
	void ShowAllTeacherCourse()const;
private:
	vector m_strVec;
};

void CTeacher::Show()const
{
	CPerson::Show();
	cout << "A teacher" << endl;
}

void CTeacher::TeacherCourse(string strCourse)
{
	this->m_strVec.push_back(strCourse);
}

void CTeacher::ShowAllTeacherCourse()const
{
	cout << m_Name << "nList of courses taugh by teacher:" << endl;
	for (size_t i = 0; i < m_strVec.size(); i++)
	{
		cout << m_strVec[i] << endl;
	}
	cout << endl;
}

class CGraduate :virtual public CPerson
{
public:
	CGraduate(string Name, int Age) :CPerson(Name, Age) {}
	void Show()const;
	void StudentCourse(string strCourse);
	void ShowAllStudyCourse()const;
private:
	vector m_strVec;
};

void CGraduate::Show()const
{
	CPerson::Show();
	cout << "A student" << endl;
}

void CGraduate::StudentCourse(string strCourse)
{
	this->m_strVec.push_back(strCourse);
}

void CGraduate::ShowAllStudyCourse()const
{
	cout << m_Name << endl << "nStudent's draft courses list:" << endl;
	for (size_t i = 0; i < m_strVec.size(); i++)
	{
		cout << m_strVec[i] << endl;
	}
	cout << endl;
}

class CGraduateTeacher :public CTeacher, public CGraduate
{
public:
	CGraduateTeacher(string Name, int Age) :
		CPerson(Name, Age), CTeacher(Name, Age), CGraduate(Name, Age) {}
	void Show()const;
};

void CGraduateTeacher::Show()const
{
	CPerson::Show();
	cout << "A Graduate teachern";
}

void ShowByPointer(CPerson* pPerson)	//虚函数
{
	pPerson->Show();
}

void ShowByReference(CPerson& person)
{
	person.Show();
}

void ShowByValue(CPerson person)
{
	person.Show();
}

int main()
{
	CStudent zhang("张三丰", 20);
	CStudent wang("王阳明", 21);
	CTeacher Li("梨落", 32);
	CGraduate Cao("曹梦洁", 20);
	CGraduateTeacher Hong("洪嘉玉", 22);

	zhang.StudyCourse("程序设计基础");
	zhang.StudyCourse("C++程序设计");
	zhang.StudyCourse("数据结构");
	wang.StudyCourse("数学");
	wang.StudyCourse("英语");
	wang.StudyCourse("物理");

	Li.TeacherCourse("数字电路");
	Li.TeacherCourse("计算机组成原理");

	zhang.ShowAllStudyCourse();
	wang.ShowAllStudyCourse();
	Li.ShowAllTeacherCourse();
	cout << endl;

	zhang.Show();
	wang.Show();
	Li.Show();
	cout << endl;

	ShowByPointer(&zhang);
	ShowByPointer(&wang);
	ShowByPointer(&Li);
	cout << endl;

	ShowByReference(zhang);
	ShowByReference(wang);
	ShowByReference(Li);
	cout << endl;

	ShowByValue(zhang);
	ShowByValue(wang);
	ShowByValue(Li);
	cout << endl;

	Cao.Show();
	Hong.Show();

	return 0;
}

3. 派生类对象的克隆

#include 
#include 
#include 
using namespace std;

class CMammal;

vector zoo;

class CMammal
{
public:	
	CMammal(string name, int age) :m_name(name), m_age(age)
	{
		zoo.push_back(this);
	}
	virtual CMammal* Clone()const = 0;
	void Show()const;
protected:
	string m_name;
	int m_age;
};

void CMammal::Show()const
{
	cout << m_name << " age: " << m_age << endl;
}

void ShowAllAnimal()
{
	for (size_t i = 0; i < zoo.size(); i++)
	{
		zoo[i]->Show();
	}
	cout << endl;
}

class CDog :public CMammal
{
public:
	CMammal* Clone()const
	{
		return new CDog(*this);	//调用拷贝构造动态生成一只狗
	}
	CDog(string name, int age) : CMammal(name, age) {}
};

class CHorse : public CMammal
{
public:
	CMammal* Clone()const
	{
		return new CHorse(*this);
	}
	CHorse(string name, int age) :CMammal(name, age) {}
};

int main()
{
	CDog a("恭喜", 12);
	CDog b("发财", 11);
	CHorse c("赤兔", 8);
	CHorse d("的卢", 10);
	size_t n = zoo.size();	//原动物数量
	for (size_t i = 0; i < n; i++)
	{
		zoo.push_back(zoo[i]->Clone());	//克隆原动物，放入zoo中
	}
	ShowAllAnimal();
	return 0;
}

4. 典型范例——各类物体面积求和

#include 
#include 
#include 
#include 
#include 
using namespace std;

const double PI = 3.1416;

class CShape
{
public:
	virtual double GetArea()const = 0;
};

class CCircle :public CShape
{
public:
	CCircle(double radius) :m_radius(radius) {}
	virtual double GetArea()const;
private:
	double m_radius;
};

double CCircle::GetArea()const
{
	return PI * m_radius * m_radius;
}

class CTriangle : public CShape
{
public:
	CTriangle(double a, double b, double c) :m_a(a), m_b(b), m_c(c) {}
	virtual double GetArea()const;
private:
	double m_a, m_b, m_c;
};

double CTriangle::GetArea()const
{
	return sqrt((m_a + m_b + m_c) *
				(m_a + m_b - m_c) *
				(m_a + m_c - m_b) *
				(m_b + m_c - m_a)) / 4.0;
}

class CRectangle :public CShape
{
public:
	CRectangle(double length, double width) :m_length(length), m_width(width) {}
	virtual double GetArea()const;
private:
	double m_length, m_width;
};

double CRectangle::GetArea()const
{
	return m_length * m_width;
}

double TotalArea(const vector& vecShapes)
{
	double dSum = 0;
	for (unsigned int i = 0; i < vecShapes.size(); i++)
	{
		dSum += vecShapes[i]->GetArea();
	}
	return dSum;
}

int main()
{
	vector vecShapes;
	string strShape;

	while (cin >> strShape)
	{
		if (strShape == "circle")
		{
			double radius;
			cin >> radius;
			vecShapes.push_back(new CCircle(radius));
		}
		else if (strShape == "triangle")
		{
			double a, b, c;
			cin >> a >> b >> c;
			vecShapes.push_back(new CTriangle(a, b, c));
		}
		else if (strShape == "rectangle")
		{
			double length, width;
			cin >> length >> width;
			vecShapes.push_back(new CRectangle(length, width));
		}
	}

	cout << fixed << setprecision(4) << TotalArea(vecShapes) << endl;

	for (unsigned int i = 0; i < vecShapes.size(); i++)
	{
		delete vecShapes[i];
	}
	return 0;
}

5. 其他继承方式

5.1 私有继承和保护继承

class 派生类名 :private 基类名
{
    ...    //私有继承
}

class 派生类名 :protected 基类名
{
    ...    //保护继承
}

• 私有继承后，基类公有成员和保护成员在派生类里成为了私有成员，也就是派生类对象不再具有基类对象所具有的功能，派生类对象不再是一种基类对象，不符合赋值兼容原则。
• 保护继承后，基类公有成员和保护成员在派生类里成为了保护成员，派生类对象不再具有基类对象所具有的功能，派生类对象不再是一种基类对象，也不符合赋值兼容原则。

#include 
#include 
using namespace std;

class CStack :private list
{
public:
	void push(int x);
	bool empty()const;
	int top()const;
	void pop();
};

void CStack::push(int x)
{
	this->push_back(x);
}

bool CStack::empty()const
{
	return (list::empty());
}

int CStack::top()const
{
	return this->back();
}

void CStack::pop()
{
	this->pop_back();
}

int main()
{
	CStack S1, S2;
	int v, x;

	while (cin >> v >> x)
	{
		if (v == 1)
		{
			S1.push(x);
		}
		else
		{
			S2.push(x);
		}
	}

	while (!S1.empty())
	{
		x = S1.top();
		cout << x << ' ';
		S1.pop();
	}
	cout << endl;

	while (!S2.empty())
	{
		x = S2.top();
		cout << x << ' ';
		S2.pop();
	}
	cout << endl;

	return 0;
}