python:类的练习

1.简易图形计算

class shape:
    def area(self):
        return 0
class  circle(shape):
    def __init__(self,r):
        self.r=r

    def area(self):
        return 3.14*self.r**2

class Rectangle(shape):
    def __init__(self,width,height):
        self.width=width
        self.height=height

    def area(self):
        return self.width*self.height

if __name__=="__main__":
    c=circle(5)
    r=Rectangle(4,5)
    print(c.area())
    print(r.area())

2.简易电商商品类

class product:
    def __init__(self,name,price):
        self.name=name
        self.price=price

    def get_price(self):
        return self.price

class DiscountProduct(product):
    def __init__(self,name,price,discount):
        super().__init__(name,price)
        self.discount=discount
    def get_price(self):#重写方法
        return self.price*(1-self.discount/100)

p=product('book',30)
print(p.get_price())#30
d=DiscountProduct('pen',10,20)
print(d.get_price())#8.0

3.重写，重定义

重写：

class Dog(object):
    counter=0
    def __init__(self,name):
        self.name=name
        Dog.counter+=1
    def greet(self):
        print(f'hi I‘m {self.name},my number is {self.counter}')

class BarkingDog(Dog):
    def greet(self):
        print('woof')#重写

if __name__=='__main__':
    dog=Dog('co')
    dog.greet()
    B=BarkingDog('N')
    B.greet()

重定义：

class Dog:
    counter=0
    def __init__(self,name):
        self.name=name
        Dog.counter+=1
    def greet(self):
        print(f'hi I‘m {self.name},my number is {self.counter}')

class BarkingDog(Dog):
    def __init__(self,name,color):
        super().__init__(name)
        self.color=color
    def greet(self):
        print(f'woof,My color is {self.color}')

if __name__=='__main__':
    d=Dog('co')
    d.greet()
    B=BarkingDog('N','red')
    B.greet()