C/C++中多重继承详解及其作用介绍

目录

• 概述
• 优缺点

• 优点
• 缺点

• 格式
• 例子

• 两个基类有同名成员
• 基类和派生类有同名成员
• 两个基类从同一个基类派生

派生类构造函数名(总形式参数表列): 
    基类1构造函数(实际参数表列),
    基类2构造函数(实际参数表列),
    基类3构造函数(实际参数表列)
{
    派生类中新增数成员据成员初始化语句
}

#ifndef PROJECT5_TEACHER_H
#define PROJECT5_TEACHER_H
#include <string>
using namespace std;
class Teacher {
protected:
    string name;
    int age;
    string title;
public:
    Teacher(string n, int a, string t);
    void display_teacher();
};
#endif //PROJECT5_TEACHER_H

#include <iostream>
#include "Teacher.h"
using namespace std;
Teacher::Teacher(string n, int a, string t) : name(n), age(a), title(t) {}
void Teacher::display_teacher() {
    cout << "Teacher name: " << name << endl;
    cout << "age: " << age << endl;
    cout << "title: " << title << endl;
}

#ifndef PROJECT5_STUDENT_H
#define PROJECT5_STUDENT_H
#include <string>
using namespace std;
class Student {
protected:
    string name;
    char gender;
    double score;
public:
    Student(string n, char g, double s);
    void display_student();
};
#endif //PROJECT5_STUDENT_H

#include <iostream>
#include "Student.h"
using namespace std;
Student::Student(string n, char g, double s) : name(n), gender(g), score(s) {}
void Student::display_student() {
    cout << "Student name: " << name << endl;
    cout << "gender: " << gender << endl;
    cout << "score: " << score << endl;
}

#ifndef PROJECT5_GRADUATE_H
#define PROJECT5_GRADUATE_H
#include "Teacher.h"
#include "Student.h"
#include <string>
using namespace std;
class Graduate : public Teacher, public Student{
private:
    double wage;
public:
    Graduate(string t_n, int t_a, string t_t, string s_n, char s_g, double s_s);
    void display_graduate();
};
#endif //PROJECT5_GRADUATE_H

#include "Graduate.h"
Graduate::Graduate(string t_n, int t_a, string t_t, string s_n, char s_g, double s_s) :
    Teacher(t_n, t_a, t_t),
    Student(s_n, s_g, s_s) {}
void Graduate::display_graduate() {
    display_teacher();
    display_student();
}

#include <iostream>
#include "Graduate.h"
using namespace std;
int main() {
    Graduate graduate1("王叔叔", 18, "隔壁老王", "我是小白呀", 'f', 99);
    graduate1.display_graduate();
    return 0;
}

Teacher name: 王叔叔
age: 18
title: 隔壁老王
Student name: 我是小白呀
gender: f
score: 99

#ifndef PROJECT5_A_H
#define PROJECT5_A_H
#include <iostream>
using namespace std;
class A {
public:
    int num;
    void display() {cout << "A's num:" << num << endl;};
};
#endif //PROJECT5_A_H

#ifndef PROJECT5_B_H
#define PROJECT5_B_H
#include <iostream>
using namespace std;
class B {
public:
    int num;
    void display() {cout << "B's num:" << num << endl;};
};
#endif //PROJECT5_B_H

#ifndef PROJECT5_C_H
#define PROJECT5_C_H
#include <iostream>
#include "A.h"
#include "B.h"
using namespace std;
class C: public A, public B{
public:
    int c;
    void display() {cout << c << endl;};
};
#endif //PROJECT5_C_H

#include <iostream>
#include "C.h"
using namespace std;
int main() {
    C c1;
    c1.A::num = 1;  // 用基类名限定
    c1.B::num = 2;  // 用基类名限定
    c1.A::display();
    c1.B::display();
    return 0;
}

A's num:1
B's num:2

#include <iostream>
#include "C.h"
using namespace std;
int main() {
    C c1;
    c1.num = 1;
    c1.display();
    return 0;
}

class A {
public:
    int num;
    void display() {cout << "A's num:" << num << endl;};
};

class B {
public:
    int num;
    void display() {cout << "B's num:" << num << endl;};
};

class C: public A, public B{
public:
    int num;
    void display() {cout << "C's num:" << num << endl;};
};

int main() {
    C c1;
    c1.num = 3;
    c1.A::num = 1;
    c1.B::num = 2;
    c1.display();
    c1.A::display();
    c1.B::display();
    return 0;
}

C's num:3
A's num:1
B's num:2

class N {
public:
    int a;
    void display(){
        cout << "A::a=" << a <<endl;
    }
};

class A : public N {
public:
    int a1;
};

class B : public N {
public:
    int a2;
};

class C: public A, public B{
public:
    int a3;
    void display() {cout << "a3=" << a3 << endl;};
};

int main() {
    C c1;
    // 合法访问
    c1.A::a = 3;
    c1.A::display();
    return 0;
}

A::a=3