C++继承与菱形继承详细介绍

//以下代码就是采用了继承机制的一个场景
class person
{
protected:
	char _name[28];
	int _age;
	char _id[30];
};
//继承是代码复用的一种重要手段
class student :public person
{
protected:
	char _academy[50]; //学院
};

class person
{
protected:
	char _name[28];
	char _id[30];
private:
	int _age;
};
class teacher :public person
{
public:
	teacher()
		:_age(0) //基类的private成员在派生类里不能访问
	{
	}
protected:
	char _jodid[20]; //工号
};
int main(void)
{
	teacher t1;
	t1._age; //基类的private成员在类外不能访问
	return 0;
}

class Person
{
protected:
	string _name; // 姓名
	string _sex; // 性别
	int _age; // 年龄
};
class Student : public Person
{
public:
	int _id; // 学号
};
int main(void)
{
	//可以将派生类赋值给基类的对象、指针、引用
	Person p;
	Student s;
	p = s;
	Person* Pptr = &s;
	Person& Refp = s;
	//注意不能将将基类对象给派生类对象
	//s = p;
	//允许将基类指针赋值给派生类指针，但是需要强制转换
	Student* sPtr = (Student*)Pptr;
	return 0;
}

//以下代码的运行结果是什么？
class Person
{
protected:
	string _name = "杨XX"; // 姓名
	int _num = 12138; // 身份证号
};
class Student : public Person
{
public:
	void Print()
	{
		cout <<_num << endl;
	}
protected:
	int _num = 52622; // 学号
};
void Test()
{
	Student s1;
	s1.Print();
};

class Person
{
protected:
	string _name = "杨XX"; // 姓名
	int _num = 12138; // 身份证号
};
class Student : public Person
{
public:
	void Print()
	{
		cout << "身份证号:" << Person::_num << endl;
		cout << "学号:" << _num << endl;
	}
protected:
	int _num = 52622; // 学号
};
void Test()
{
	Student s1;
	s1.Print();
};
int main(void)
{
	Test();
	return 0;
}

//以下的两个函数构成隐藏还是重载？
class A
{
public:
	void func()
	{
		cout << "func()" << endl;
	}
};
class B : public A
{
public:
	void func(int num)
	{
		cout << "func(int num)" << endl;
	}
};
void Test()
{
	B b;
	b.func(10);
}

```cpp
//以下代码的运行结果是什么？
class A
{
public:
	void func()
	{
		cout << "func()" << endl;
	}
};
class B : public A
{
public:
	void func(int num)
	{
		cout << "func(int num)" << endl;
	}
};
void Test()
{
	B b;
	b.func();
}

//如果需要自己实现派生类的几个四个重点默认成员函数，需要如何实现？该注意什么？
class Person
{
public:
	Person(const char* name)
		:_name(name)
	{
		cout << "Person(const char* name)" << endl; //方便查看它什么被调用了
	}
	Person(const Person& p)
		:_name(p._name)
	{
		cout << "Person(const Person& p)" << endl;
	}
	Person& operator=(const Person& p)
	{
		cout << "Person& operator=(const Person& p)" << endl;
		//首先排除自己给自己赋值
		if (this != &p)
		{
			_name = p._name;
		}
		return *this;
	}
	~Person()
	{
		cout << "~Person()" << endl; 
	}
protected:
	string _name; //姓名
};
class Student : public Person
{
protected:
	int _id; //学号
	int* _ptr = new int[10]; //给一个需要自己实现默认成员函数场景用以举例
};

class Student : public Person
{
public:
	Student(const char* name, int id)
		: Person(name)
		, _id(id)
	{
		cout << "Student()" << endl;
	}
	Student(const Student& s)
		: Person(s)
		, _id(s._id)
	{
		cout << "Student(const Student& s)" << endl;
	}
	Student& operator = (const Student& s)
	{
		cout << "Student& operator= (const Student& s)" << endl;
		if (this != &s)
		{
			Person::operator =(s);
			_id = s._id;
		}
		return *this;
	}
	~Student()
	{
		cout << "~Student()" << endl;
	}
protected:
	int _id; //学号
};

class Person
{
public:
	string _name; // 姓名
};
class Student : public Person
{
public:
	int _num; //学号
};
class Teacher : public Person
{
public:
	int _id; // 职工编号
};
class Assistant : public Student, public Teacher
{
public:
	string _majorCourse; // 主修课程
};
int main()
{
	// 二义性、数据冗余
	Assistant a;
	a._id = 1;
	a._num = 2;
	// 这样会有二义性无法明确知道访问的是哪一个
	a._name = "peter";
	return 0;
}

int main()
{
	// 二义性、数据冗余
	Assistant a;
	a._id = 1;
	a._num = 2;
	a.Student::_name = "小张";
	a.Teacher::_name = "张老师";
	return 0;
}

class A {
public:
	int _a;
};
class B : public A{
public:
	int _b;
};
class C : public A{
public:
	int _c;
};
class D : public B, public C {
public:
	int _d;
};
int main()
{
	D d;
	d.B::_a = 1;
	d.C::_a = 2;
	d._b = 3;
	d._c = 4;
	d._d = 5;
	return 0;
}

class A {
public:
	int _a;
};
class B : virtual public A {
public:
	int _b;
};
class C : virtual public A {
public:
	int _c;
};
class D : public B, public C {
public:
	int _d;
};
int main()
{
	D d;
	d.B::_a = 1;
	d.C::_a = 2;
	d._b = 3;
	d._c = 4;
	d._d = 5;
	return 0;
}

class head
{
private:
	int _eye;
	int _ear;
	int _mouth;
};
class hand
{
private:
	int _arm;
	int _fingers;
};
class Person
{
	//组合
	//一个人由手、头等组合
	hand _a;
	head _b;
};