class:关键字

具有封装，继承，多态

就比方说 有一个类 叫做 car
这个类的属性 可以有 color size brand price year 等描述性的东西
这个类的方法 可以是 run stop forward backward 等执行性的东西
class car:

定义基本属性

color = ''  
size = 0  
brand = ''
price = 0 
year = 0 

定义构造方法

def __init__(self):  
    self.color = color
    self.size = size
    self.brand = brand
    self.price = price
    self.year = year
def run(self):  
    print("the car is running" )
def stop(self):  
    print("the car is stop" )
def forward(self):  
    print("the car is forward" )
def backward(self):  
    print("the car is backward" )

类调用

benz = car('red',1.8T,'Mercedes',400000,2016)
benz.run()
benz.stop()
benz.forward()
benz.backward()