C++快速入门---多继承（20）

C++快速入门---多继承（20）

只要你遇到的问题无法只用一个“是一个”关系来描述的时候，就是多继承出场的时候。

例子：

有一部分学生还教课挣钱（助教），这样就存在了即是老师又是学生的复杂关系，也就是同时存在着两个“是一个”关系。

我们需要写一个TeachingStudent类让它同时继承Teacher类和Student类，换句话说，就是需要使用多继承。

基本语法：

class TeachingStudent : public Student, public Teacher

{...}

代码如下：

#include <iostream>
#include <string>

class Person
{
public:
	Person(std::string theName);
	
	void introduce();
	
protected:
	std::string name;
};

class Teacher : public Person
{
public:
	Teacher(std::string theName, std::string theClass);
	
	void teach();
	void introduce();

protected:
	std::string classes;
};

class Student : public Person
{
public:
	Student(std::string theName, std::string theClass);
	
	void attendClass();
	void introduce();

protected:
	std::string classes;
};

//助教 
class TeachingStudent : public Student, public Teacher
{
public:
	TeachingStudent(std::string theName, std::string classTeaching, std::string classAttending);

	void introduce();	
};

Person::Person(std::string theName)
{
	name = theName;
}

void Person::introduce()
{
	std::cout << "大家好，我是" << name << ".\n\n";
}

Teacher::Teacher(std::string theName, std::string theClass) : Person(theName)
{
	classes = theClass;
}

void Teacher::teach()
{
	std::cout << name << "教" << classes << ".\n\n";
}

void Teacher::introduce()
{
	std::cout << "大家好,我是" << name << ",我教" << classes << ".\n\n";
}

Student::Student(std::string theName, std::string theClass) : Person(theName)
{
	classes = theClass;
}

void Student::attendClass()
{
	std::cout << name << "加入" << classes << "学习.\n\n";
}

void Student::introduce()
{
	std::cout << "大家好,我是" << name << ",我在" << classes << "学习.\n\n";
}

TeachingStudent::TeachingStudent(std::string theName,
								 std::string classTeaching,
								 std::string classAttending)
								 : Teacher(theName, classTeaching), Student(theName, classAttending)
{
}

void TeachingStudent::introduce()
{
	std::cout << "大家好,我是" << Student::name << ".我教" << Teacher::classes << ",";
}

int main()
{
	Teacher teacher("小甲鱼", "C++入门班");
	Student student("迷途羔羊", "C++入门班");
	TeachingStudent teachingStudent("丁丁", "C++入门班", "C++进阶版"); 
	
	teacher.introduce();
	teacher.teach();
	student.introduce();
	student.attendClass();
	teachingStudent.introduce();
	teachingStudent.teach();
	teachingStudent.attendClass();
	
	return 0;
}