c++纯虚函数

打造c++抽象类

与其他语言的抽象类相似，抽象类不能实例化，也不能作为函数的参数，只可以作为指针类型或者引用类型

抽象类的基本特征

#pragma once
#include<iostream>
using namespace std;
class jetplane
{
private:
protected:
public:
    virtual void loadweapon(string type,int num)=0;//最显著特征，成员函数声明为virtual，并且等于0
    virtual void warfare()=0;
};

当然抽象类不能实例化

#include<iostream>
#include"jetplane.h"
void main()
{
    jetplane tornado();
}

报错：

严重性代码说明项目文件行禁止显示状态
错误 C2259 “jetplane”: 不能实例化抽象类 myabstractcls c:usersadministratorsource eposmyabstractclsmyabstractclsmymain.cpp 5

2.解决多重继承的二义性问题

目前，要求多重继承的类有共同的基类，否则多重继承的二义性仍旧无法解决

实例化的类可以作为抽象类的接口使用

声明类mig31

#pragma once
#include<iostream>
#include<string>
#include"jetplane.h"
using namespace std;
class mig31:public jetplane
{
private:
    string name;
    string origin;
    int num;
    string weaponset;
protected:
public:
    mig31::mig31(string name,string origin)
    {
        this->name = name;
        this->origin = origin;
        cout << "装备了" << this->name << "战机：原产国：" << this->origin << endl;
    }
    void loadweapon(string type, int num)
    {

    }
    void warning()
    {
        cout << this->name << "战机飞行员：" << "你已进俄罗斯空天军火力范围，我方奉命将你击落" << endl;
    }
    void warfare(string weaponset,int num)
    {
        cout<<this->name<< "战机发射了"<< weaponset<<"数量"<<num << endl;
    }

};

声明类JAS-39

class jas39:public jetplane
{
private:
    string name;
    string origin;
    int num;
    string weaponset;
protected:
public:
    jas39::jas39(string name,string origin)
    {
        this->name = name;
        this->origin = origin;
        cout << "装备了" << this->name << "战机：原产国：" << this->origin << endl;
    }
    void warning()
    {
        cout << this->name << "战机飞行员：" << "你已进入瑞典领空，请迅速撤离，这是来自瑞典皇家空军的警告" << endl;
    }

    void loadweapon(string type, int num)
    {

    }

    void warfare(string weaponset,int num)
    {
        cout<<this->name<< "战机发射了"<< weaponset<<"数量"<<num << endl;
    }

};

声明类f-15

class f15:public jetplane
{
private:
    string name;
    string origin;
    int num;
    string weaponset;
protected:
public:
    f15::f15(string name,string origin)
    {
        this->name = name;
        this->origin = origin;
        cout << "装备了" << this->name << "战机：原产国：" << this->origin << endl;
    }
    void warning()
    {
        cout << this->name << "战机飞行员：" << "乳罩呼叫内裤~乳罩呼叫内裤~，俄国人的轰炸机逼近阿拉斯加，是否给他们点儿颜色？" << endl;
    }
    
    void loadweapon(string type, int num)
    {

    }
    
    void warfare(string weaponset,int num)
    {
        cout  <<this->name<< "战机发射了"<< weaponset<<"数量"<<num << endl;
    }

};

声明JH-7

class jh7:public jetplane
{
private:
    string name;
    string origin;
    int num;
    string weaponset;
protected:
public:
    jh7::jh7(string name,string origin)
    {
        this->name = name;
        this->origin = origin;
        cout << "装备了" << this->name << "战机：原产国：" << this->origin << endl;
    }
    void warning()
    {
        cout << this->name << "战机飞行员：" << "你已进东海防空识别区，人民解放军空军奉命将你方驱离，请立刻离开我方空域" << endl;
    }
    void loadweapon(string type, int num)
    {

    }
    void warfare(string weaponset,int num)
    {
        cout<<this->name<< "战机发射了"<< weaponset<<"数量"<<num << endl;
    }

};

在主程序文件中调用

#include<iostream>
#include"jetplane.h"
#include"mig31.h"
#include"f15.h"
#include"jh7.h"
#include"jas39.h"

void warning(jetplane *fighter)
{
    fighter->warning();
}

void main()
{
    jetplane *fighter =NULL;
    f15 hawk("F-15", "美国");
    mig31 foxbat("米格-31","苏联");
    jas39 gripen("JAS-39鹰狮","瑞典");
    jh7 flyleopard("JH-7飞豹", "中国");
    fighter = &hawk;
    fighter->warning();
    fighter = &foxbat;
    fighter->warning();
    fighter = &gripen;
    fighter->warning();
    fighter = &flyleopard;
    fighter->warning();
    system("pause");
}

输出结果：

装备了F-15战机：原产国：美国
装备了米格-31战机：原产国：苏联
装备了JAS-39鹰狮战机：原产国：瑞典
装备了JH-7飞豹战机：原产国：中国
F-15战机飞行员：乳罩呼叫内裤~乳罩呼叫内裤~，俄国人的轰炸机逼近阿拉斯加，是否给他们点儿颜色？
米格-31战机飞行员：你已进俄罗斯空天军火力范围，我方奉命将你击落
JAS-39鹰狮战机飞行员：你已进入瑞典领空，请迅速撤离，这是来自瑞典皇家空军的警告
JH-7飞豹战机飞行员：你已进东海防空识别区，人民解放军空军奉命将你方驱离，请立刻离开我方空域
请按任意键继续. . .