C++快速入门---虚继承(21)
通过虚继承某个基类,就是在告诉编译器,从当前这个类再派生出来的子类只能拥有那个基类的一个实例。
虚继承的语法:
class Teacher : virtual public Person
{ ... }
让Student类和Teacher类都虚继承自Person类,编译器将确保从Student和Teacher类再派生出来的子类只能拥有一份Person类的属性。
代码如下:
#include <iostream>
#include <string>
class Person
{
public:
Person(std::string theName);
void introduce();
protected:
std::string name;
};
//虚继承
class Teacher : virtual public Person
{
public:
Teacher(std::string theName, std::string theClass);
void teach();
void introduce();
protected:
std::string classes;
};
//虚继承
class Student : virtual 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";
}
//因为Teacher和Student都是虚继承,不能拥有Person类的拷贝(备份),所以需要调用Person的构造方法
TeachingStudent::TeachingStudent(std::string theName,
std::string classTeaching,
std::string classAttending)
:
Teacher(theName, classTeaching),
Student(theName, classAttending),
Person(theName)
{
}
void TeachingStudent::introduce()
{
std::cout << "大家好,我是" << name << ".我教" << Teacher::classes << ",";
std::cout << "同时我在" << Student::classes << "学习.\n\n";
}
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;
}