01 多态的基本概念
02 多态案例,计算器实现
03 纯虚函数和抽象类
04 多态案例2 制作饮品
05 虚析构和纯虚析构
06 案例三-电脑组装
01 多态的基本概念
#include<iostream>
using namespace std;
class Animal
{
public:
virtual void speak()
{
cout << "动物叫声" << endl;
}
};
class Cat: public Animal
{
public:
void speak()
{
cout << "小猫在叫" << endl;
}
};
class Dog : public Animal
{
public:
void speak()
{
cout << "小狗在叫" << endl;
}
};
//执行说话函数
//地址早绑定 在编译阶段确定函数地址
//如果想执行让猫说话,那么这个函数地址就不能提前绑定,需要在运行阶段进行绑定,地址晚绑定
//动态多态满足条件
//1.有继承条件
//2.子类重新写父类的虚函数
//动态多态使用
//父类的指针或者引用, 执行子类对象
void dospeak(Animal &animal)
{
//重写.函数返回值类型 函数名 参数列表 完全相同
animal.speak();
}
void test1()
{
Cat cat;
dospeak(cat);
Dog dog;
dospeak(dog);
}
int main()
{
test1();
system("pause");
return 0;
}
02 多态案例,计算器实现
#include<iostream>
using namespace std;
//利用多态实现计算器
//好处:
//1.组织结构清晰
//2.可读性强
//3.对前期和后期扩展及维护性高
//实现计算器抽象类
class Calculation
{
public:
virtual int getResult()
{
return 0;
}
int a;
int b;
};
//加法类实现
class AddCalculation :public Calculation
{
public:
int getResult()
{
return a + b;
}
};
//减法类实现
class SubCalculation :public Calculation
{
public:
int getResult()
{
return a - b;
}
};
//乘法类实现
class MultCalculation :public Calculation
{
public:
int getResult()
{
return a * b;
}
};
void test()
{
//多态使用条件
//父类指针或者引用指向子类对象
//加法运算
Calculation* abc = new AddCalculation;
abc->a = 100;
abc->b = 200;
cout << abc->a << "+" << abc->b << "=" << abc->getResult()<< endl;
//用完后销毁
delete abc;
//减法运算
abc = new SubCalculation;
abc->a = 100;
abc->b = 200;
cout << abc->a << "-" << abc->b << "=" << abc->getResult() << endl;
delete abc;
//乘法运算
abc = new MultCalculation;
abc->a = 100;
abc->b = 200;
cout << abc->a << "*" << abc->b << "=" << abc->getResult() << endl;
delete abc;
}
int main()
{
test();
system("pause");
return 0;
}
//总结:c++开发提倡利用多态程序架构,因为优点很多
03 纯虚函数和抽象类
#include<iostream>
using namespace std;
//纯虚函数和抽象类
class Base
{
public:
//纯虚函数
//只要有一个纯虚函数,这个类称为抽象类
//抽象类特点; virtual 类型 函数()=0
//1.无法实例化对象
//2.抽象类的子类,必须重写父类的纯虚函数,否则属于抽象类
virtual void getResult() = 0;
};
class Son :public Base
{
public:
virtual void getResult()
{
cout << "getResult调用" << endl;
}
};
void test()
{
//Base b; //抽象类是无法实例化对象的
//2.抽象类的子类,必须重写父类的纯虚函数,否则属于抽象类
Base* b = new Son;
b->getResult();
}
int main()
{
test();
system("pause");
return 0;
}
04 多态案例2 制作饮品
#include<iostream>
using namespace std;
class AllDrinking
{
public:
//1.煮
virtual void boil() = 0;
//2.冲水
virtual void brew() = 0;
//3.倒入杯中
virtual void pour() = 0;
//4.加其他作料
virtual void add() = 0;
//制作饮品
void make()
{
boil();
brew();
pour();
add();
}
};
//制作咖啡
class Coffee : public AllDrinking
{
string name = "咖啡";
virtual void boil()
{
cout << name << "开始倒水" << endl;
}
virtual void brew()
{
cout << name << "开始冲水" << endl;
}
virtual void pour()
{
cout << name << "倒入杯中" << endl;
}
virtual void add()
{
cout << name << "加入其他调料" << endl;
}
};
//制作柠檬
class Lemon: public AllDrinking
{
string name = "柠檬";
virtual void boil()
{
cout << name << "开始倒水" << endl;
}
virtual void brew()
{
cout << name << "开始冲水" << endl;
}
virtual void pour()
{
cout << name << "倒入杯中" << endl;
}
virtual void add()
{
cout << name << "加入其他调料" << endl;
}
};
//制作函数
void dowork(AllDrinking * abs)
{
abs->make();
delete abs; //释放
}
void test1()
{
//制作咖啡
dowork(new Coffee);
cout << "---------------" << endl;
//制作柠檬
dowork(new Lemon);
}
int main()
{
test1();
system("pause");
return 0;
}
05 虚析构和纯虚析构
#include<iostream>
using namespace std;
class Animal
{
public:
Animal()
{
cout << "Animal构造函数" << endl;
}
virtual void speak() = 0;
//虚构析构函数
//利用虚析构可以解决,父类指针释放1子类对象时不干净的问题
/*virtual ~Animal()
{
cout << "Animal析构函数" << endl;
}*/
//纯虚构析构函数, 需要声明也需要实现
//有了纯虚构后,这个属于抽象类,无法实现实例化对象
virtual ~Animal() = 0;
};
Animal::~Animal()
{
cout << "Animal纯析构函数" << endl;
}
class Cat :public Animal
{
public:
Cat(string n)
{
cout << "Cat的构造函数" << endl;
name = new string(n);
}
virtual void speak()
{
cout << *name << "小猫在说话" << endl;
}
~Cat()
{
if (name != NULL)
{
delete name;
name = NULL;
}
cout << "Cat的析构函数" << endl;
}
string* name;
};
void test1()
{
Animal* a = new Cat("汤姆");
a->speak();
//父类指针在析构时候,不会调用子类中析构函数,导致子类如果有堆区属性,出现内存泄露
delete a;
}
int main()
{
test1();
system("pause");
return 0;
}
//总结:
//1.虚析构或纯虚析构就是用来解决通过父类指针释放子类对象
//2.如果子类中没有堆区数据，可以不写为虚析构或纯虚析构
//3.拥有纯虚析构函数的类也属于抽象类
06 案例三-电脑组装
#include<iostream>
using namespace std;
//抽象cpu类
class Cpu
{
public:
//抽象计算函数
virtual void calculate() = 0;
};
//抽象显卡类
class VideoCard
{
public:
//抽象显示函数
virtual void display() = 0;
};
//抽象内存条类
class Memory
{
public:
//抽象存储函数
virtual void storage() = 0;
};
//电脑类
class Compute
{
public:
Compute(Cpu *cpu, VideoCard *videocard, Memory *memory)
{
m_cpu = cpu;
m_videocard = videocard;
m_memory = memory;
}
//提供工作函数
void work()
{
//让零件工作起来,调用接口
m_cpu->calculate();
m_videocard->display();
m_memory->storage();
}
//提供析构函数释放3个电脑零件
~Compute()
{
if (m_cpu != NULL)
{
delete m_cpu;
m_cpu = NULL;
}
if (m_videocard != NULL)
{
delete m_videocard;
m_videocard = NULL;
}
if (m_memory != NULL)
{
delete m_memory;
m_memory = NULL;
}
}
private:
Cpu *m_cpu; //cpu零件指针
VideoCard *m_videocard; //显卡零件指针
Memory *m_memory; //内存条零件指针
};
//amd
class Amdcpu :public Cpu
{
public:
virtual void calculate()
{
cout << "Amdcpu开始工作" << endl;
}
};
class Amdvd : public VideoCard
{
public:
virtual void display()
{
cout << "Amd显卡开始工作" << endl;
}
};
class Amdmem : public Memory
{
public:
virtual void storage()
{
cout << "Amd内存条开始工作" << endl;
}
};
//intel
class Intelcpu :public Cpu
{
public:
virtual void calculate()
{
cout << "因特尔cpu开始工作" << endl;
}
};
class Intelvd : public VideoCard
{
public:
virtual void display()
{
cout << "因特尔显卡开始工作" << endl;
}
};
class Intelmem : public Memory
{
public:
virtual void storage()
{
cout << "因特尔内存条开始工作" << endl;
}
};
void test01()
{
cout << "第一台电脑开始工作" << endl;
//第一台电脑零件
Cpu* ic = new Intelcpu;
VideoCard *iv = new Intelvd;
Memory *im = new Intelmem;
//创建第一台电脑
Compute* compute = new Compute(ic, iv, im);
compute->work();
delete compute;
cout << "第二台电脑开始工作" << endl;
//第二台电脑组装
Cpu* ac = new Amdcpu;
VideoCard* av = new Amdvd;
Memory* am = new Amdmem;
Compute* compute2 = new Compute(ac, av, am);
compute2->work();
delete compute2;
cout << "第三台电脑开始工作" << endl;
//第三台电脑组装
Compute* compute3 = new Compute(new Intelcpu, new Amdvd, new Amdmem);
compute3->work();
delete compute3;
}
int main()
{
test01();
system("pause");
return 0;
}
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