# 面向对象实战练习 | 手把手教你入门Python之七十七

## 面向对象案例练习

1、定义一个点类 Pointer

1、求圆的面积
2、求圆的周长
3、求指定点与圆的关系

import math

class Pointer(object):
def __init__(self, x, y):
self.x = x
self.y = y

class Circle(object):
self.cp = cp

def get_area(self):
return self.radius ** 2 * math.pi

def get_length(self):
return math.pi * 2 * self.radius

def relationship(self, point):
"""
求一个点和圆的关系。有三种关系：在圆内，在圆外，在圆上
:param point:  需要判断的点
:return:
"""
# 计算圆心到point的距离
distance = (point.x - self.cp.x) ** 2 + (point.y - self.cp.y) ** 2
if distance > self.radius ** 2:
print('在圆外')
elif distance < self.radius ** 2:
print('在圆内')
else:  # 等于的情况
print('在圆上')

p = Pointer(3, 4)  # 创建了一个Pointer对象
c = Circle(p, 5)   # 创建好的Pointer对象传递给了Circle对象c

print(c.get_area())   # 78.53981633974483
print(c.get_length())  # 31.41592653589793

p1 = Pointer(10, 10)
c.relationship(p1)    # 在圆外

p2 = Pointer(2, 2)
c.relationship(p2)   # 在圆内

p3 = Pointer(0, 0)
c.relationship(p3)   # 在圆上

2、宠物店类 PetShop

class PetShop(object):
def __init__(self, shop_name, pet_list=None):
self.shop_name = shop_name
if pet_list is None:
pet_list = []
self.pet_list = pet_list

# def __init__(self, shop_name):
# self.shop_name = shop_name
# self.pet_list = []

def show_pets(self):
if len(self.pet_list) == 0:
print('本店还没有宠物')
return

print('{}有{}个宠物，它们是：'.format(self.shop_name, len(self.pet_list)))
for pet in self.pet_list:
# print('姓名:{},性别:{},品种:{},年龄:{}'.format(pet.name, pet.gender, pet.breed, pet.age))
print(pet)

class Pet(object):
def __init__(self, name, gender, age, breed):
self.name = name
self.gender = gender
self.age = age
self.breed = breed

def bark(self):
print(self.name + '正在叫')

def eat(self):
print(self.name+'正在吃东西')

def __str__(self):
return '姓名:{},性别:{},品种:{},年龄:{}'.format(self.name, self.gender, self.breed, self.age)

class PetDog(Pet):

def bark(self):
print(self.name+'正在汪汪汪')

def build_home(self):
print(self.name+'正在拆家')

def eat(self):
print(self.name+'正在啃骨头')

class PetCat(Pet):
def __init__(self, name, gender, age, breed, eyes_color):
super(PetCat, self).__init__(name, gender, age, breed)
self.eyes_color = eyes_color

def bark(self):
print(self.name+'正在喵喵喵')

def sajiao(self):
print(self.name+'正在撒娇')

def eat(self):
print(self.name+'正在吃鱼')

def __str__(self):
x = super(PetCat, self).__str__()
x += ",眼睛颜色:{}".format(self.eyes_color)
return x

class PetBird(Pet):
pass

dog1 = PetDog('大黄', 'female', 3, '哈士奇')
dog2 = PetDog('二黄', 'male', 2, '萨摩耶')
cat1 = PetCat('tom', 'male', 2, '英短', 'blue')
cat2 = PetCat('包子', 'female', 3, '加菲猫', 'black')

ps = PetShop('萌宠', [dog1, dog2, cat1, cat2])
ps.show_pets()

3、打印列表

class Person(object):
def __init__(self, name, age):
self.name = name
self.agae = age

def __repr__(self):
return '姓名:{},年龄:{}'.format(self.name, self.age)    # [姓名:张三,年龄:18,姓名:李四,年龄:20]

p1 = Person('张三', 18)
p1 = Person('李四', 20)

persons = [p1, p2]

# 直接打印列表，会调用列表里元素的 __repr__ 方法
# print(persons)    # 直接打印一个列表，会把列表里的每一个对象的内存地址打印出来

4、1.学生类Student：

1.查看该班级中的所有学生的信息
2.查看指定学号的学生信息
3.查看班级中成绩不及格的学生信息
4.将班级中的学生按照成绩降序排序

class Student(object):
def __init__(self, number, name, age, gender, score):
self.number = number
self.name = name
self.age = age
self.gender = gender
self.score = score

def __str__(self):
return '编号:{},姓名:{},年龄:{},性别:{},分数:{}'.format(self.number, self.name, self.age, self.gender, self.score)

def __init__(self, name, students):
self.name = name
self.students = students

def show_all(self):
for student in self.students:
print(student)

def failed_student(self):
result = filter(lambda student: student.score < 60, self.students)
for x in result:
print(x)

def order_student(self):
# self.students.sort(key = lambda s: s.score, reverse = True)  # 直接修改 self.students
return sorted(self.students, key = lambda s: s.score, reverse = True)

def get_student_by_number(self, n):
for s in self.students:
if s.number == n:
return s
else:
return '用户未找到'

# 如果数字以0开头，在python2里表示八进制
s1 = Student(1, 'zhangsan', 18, 'male', 80)
s2 = Student(5, '李四', 19, 'male', 50)
s3 = Student(10, 'tony', 20, 'male', 70)
s4 = Student(7, 'jack', 18, 'female', 90)
s5 = Student(4, 'henry', 19, 'female', 56)

g = Grade('中二班', [s1, s2, s3, s4, s5])
g.show_all()
g.failed_student()
# g.order_students()
# for student in g.students:
# print(student)

x = g.order_student()
for student in x:
print(student)

print(g.get_student_by_number(1))

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