纯虚函数和抽象类
- C面向接口编程和C多态
- 函数类型语法基础
- 函数指针做函数参数(回调函数)思想剖析
- 函数指针做函数参数两种用法（正向调用、反向调用）
- 纯虚函数 抽象类
- 抽象类基本概念
- 抽象类在多继承中的应用
- 面向抽象类编程案例强化
- C面向接口编程和C多态
#define _CRT_SECURE_NO_WARNINGS
#include <iostream>
using namespace std;
//图形类
//如果说一个类 拥有一个纯虚函数
//就称这个类是一个抽象类。
//不管这个类中有没有成员属性，只要这个类有纯虚函数，就是一个抽象类， 抽象类就是不能够实例化的。
class Shape
{
public:
//求图形面积的方法
//表示图形类声明一个方法getArea（），它是一个纯虚函数，没有函数的实现。
virtual double getArea() = 0;
};
//三角形
class Tri :public Shape
{
public:
Tri(int a, int h)
{
this->a = a;
this->h = h;
}
virtual double getArea() {
cout << "三角形求面价" << endl;
return 0.5*a*h;
}
private:
int a;
int h;
};
//正方形：
//如果说一个普通类，继承拥有纯虚函数的类，如果说不重写纯虚函数，依然是一个抽象类。
//依然不能被实例化， 如果想实例化， 必须要重写这个父类中所有纯虚函数
class Rect : public Shape
{
public:
Rect(int a) {
this->a = a;
}
virtual double getArea() {
cout << "正方形求面积" << endl;
return a*a;
}
private:
int a;//正方形边长
};
class Circle :public Shape
{
public:
Circle(int r)
{
this->r = r;
}
virtual double getArea()
{
cout << "圆形求面积" << endl;
return 3.14*r * 4;
}
private:
int r;
};
//面向抽象类写一个架构函数
void printArea(Shape *sp)
{
sp->getArea();
}
//业务层 面向的抽象类编程
int main(void)
{
//main 中所有使用的变量类型 都是 抽象类Shape的类型。
Shape *sp1 = new Rect(10);
//sp1->getArea();
Shape *sp2 = new Circle(20);
//sp2->getArea();
Shape *sp3 = new Tri(10, 20);
//sp3->getArea();
printArea(sp1);
printArea(sp2);
printArea(sp3);
return 0;
}
上一个知识的小练习
#define _CRT_SECURE_NO_WARNINGS
#include <iostream>
using namespace std;
//大哥的虚衔
class BigBrother
{
public:
//会打人。
virtual void fightPeople() = 0;
};
//东方不败
class EastNeverLose :public BigBrother
{
public:
virtual void fightPeople() {
cout << "使用了葵花宝典区打人" << endl;
}
};
//无崖子
class Wuyazi :public BigBrother
{
public:
virtual void fightPeople() {
cout << "使用北冥神功打人" << endl;
}
};
//boss
int main(void)
{
BigBrother *bigbrother = new Wuyazi;
//大哥你给我去打人。
bigbrother->fightPeople();
delete bigbrother;
return 0;
}
纯虚函数和多继承
#define _CRT_SECURE_NO_WARNINGS
#include <iostream>
using namespace std;
//接口1
class Interface1
{
public:
virtual void func1(int a, int b) = 0;
virtual void func3(int a, int b) = 0;
};
//接口2
class Interface2
{
public:
virtual void func2(int a) = 0;
};
class Child :public Interface1, public Interface2
{
public:
virtual void func1(int a, int b)
{
cout << "func1" << endl;
}
virtual void func3(int a, int b) {
cout << "func3" << endl;
}
virtual void func2(int a)
{
cout << "func2 " << endl;
}
};
int main(void)
{
Interface1 *if1 = new Child;
if1->func1(10, 20);
if1->func3(100, 200);
Interface2 *if2 = new Child;
if2->func2(10);
return 0;
}
电脑组装--小练习
#define _CRT_SECURE_NO_WARNINGS
#include <iostream>
using namespace std;
//-------- 抽象层---------
//抽象CPU类
class CPU
{
public:
CPU();
virtual void caculate() = 0;
};
//抽象的card类
class Card
{
public:
virtual void display() = 0;
};
//抽象的内存类
class Memory
{
public:
virtual void storage() = 0;
};
//架构类
class Computer
{
public:
Computer(CPU *cpu, Card *card, Memory *mem)
{
this->cpu = cpu;
this->card = card;
this->mem = mem;
}
void work()
{
this->cpu->caculate();
this->card->display();
this->mem->storage();
}
~Computer() {
if (this->cpu != NULL) {
delete this->cpu;
}
if (this->card != NULL) {
delete this->card;
}
if (this->mem != NULL) {
delete this->mem;
}
}
private:
CPU* cpu;
Card*card;
Memory *mem;
};
// --------------------------
//-----------实现层----------
//具体的IntelCPU
class IntelCPU :public CPU
{
public:
virtual void caculate() {
cout << "Intel CPU开始计算了" << endl;
}
};
class IntelCard :public Card
{
public:
virtual void display() {
cout << "Intel Card开始显示了" << endl;
}
};
class IntelMem :public Memory {
public:
virtual void storage() {
cout << "Intel mem开始存储了" << endl;
}
};
class NvidiaCard :public Card
{
public:
virtual void display() {
cout << "Nvidia 显卡开始显示了" << endl;
}
};
class KingstonMem :public Memory {
public:
virtual void storage() {
cout << "KingstonMem 开始存储了" << endl;
}
};
//--------------------------
//--------业务层-------------------
int main(void)
{
//1 组装第一台intel系列的电脑
#if 0
CPU *intelCpu = new IntelCPU;
Card *intelCard = new IntelCard;
Memory *intelMem = new IntelMem;
Computer *com1 = new Computer(intelCpu, intelCard, intelMem);
com1->work();
Card *nCard = new NvidiaCard;
Memory* kMem = new KingstonMem;
Computer *com2 = new Computer(intelCpu, nCard, kMem);
com2->work();
delete intelCpu;
#endif
Computer *com1 = new Computer(new IntelCPU, new IntelCard, new IntelMem);
com1->work();
delete com1;
return 0;
}