类和对象：继承

读书笔记：

我的代码：

# -*- coding: gbk -*-import mathclass Point():    def __init__(self,x,y):        self.x = x        self.y = yclass Line():    def __init__(self,p1,p2):        self.p1 = p1        self.p2 = p2    def getLength(self):        return math.sqrt((self.p1.x-self.p2.x)**2+\        (self.p1.y-self.p2.y)**2)p1 = Point(1,1)p2 = Point(7,9)line = Line(p1,p2)print("线段的长度是：%.2f"%line.getLength())