1.声明一个电脑类: 属性:品牌、颜色、内存小 方法:打游戏、写代码、看视频

class Computer:
    """电脑类"""

    def __init__(self, brand='', color='黑色', ram=4):
        self.brand = brand
        self.color = color
        self.ram = ram

    @staticmethod
    def play_game():
        print('打游戏')


com1 = Computer('外星人', ram=32)
print(com1.color)
print(getattr(com1, 'color'))

com1.owner = '余婷'
setattr(com1, 'size', 15.6)
print(com1.owner, com1.size)

del com1.owner
delattr(com1, 'size')

2.声明个人的类和狗的类:

狗的属性:名字、颜色、年龄
狗的方法:叫唤
人的属性:名字、年龄、狗人的方法:遛狗
创建人的对象小明，让他拥有一条狗大黄，然后让小明去遛大黄

class Dog:
    def __init__(self, name, color='黄色'):
        self.name = name
        self.age = 0
        self.color = color

    def bark(self):
        print('%s在嗷嗷加！' % self.name)


class Person:
    def __init__(self, name, age=0, dog=None):
        self.name = name
        self.age = age
        self.dog = dog

    def walk_dog(self):
        if self.dog:
            print('%s牵着%s在散步' % (self.name, self.dog.name))
        else:
            print('没有狗！遛自己~')


p1 = Person('小明', 18)
dog1 = Dog('大黄')
p1.dog = dog1
p1.walk_dog()

3.声明一个圆类，自己确定有哪些属性和方法

class Circle:
    """圆类"""
    Pi = 3.14

    def __init__(self,ridius):
        self.ridius = ridius

    def area(self):
        return Circle.Pi * self.ridius **2

    def perimeter(self):
        return Circle.Pi * self.ridius * 2


cir1 = Circle(5)

print(cir1.area())  # 78.5
print(cir1.perimeter())  # 31.400000000000002

4.创建一个学生类:

属性:姓名，年龄，分数

方法:答到，展示学生信息

创建一个班级类:
属性:学生，班级名
方法:添加学生，删除学生，点名, 求班上学生的平均年龄

class Student:
    def __init__(self, name, age=0, num='0001'):
        self.name = name
        self.age = age
        self.num = num
        self.state = randint(0, 1)    # 是否在教室的状态， 0 -> 不在, 1 -> 在

    def amount(self):
        print('%s 到!' % self.name)

    def show(self):
        print('姓名:%s 年龄:%d 学号:%s' % (self.name, self.age, self.num))


class Class:
    def __init__(self, name):
        self.students = [
            Student('stu1', 19, '001'),
            Student('stu2', 20, '002'),
            Student('stu3', 23, '003'),
            Student('stu1', 19, '004'),
            Student('stu4', 30, '005'),
        ]
        self.name = name
        # 学号生成器
        self.__nums = ('stu'+str(num).zfill(3) for num in range(50))

    # 添加学⽣生
    def add_student(self):
        # 输入学生信息
        stu_name = input('姓名:')
        stu_age = int(input('年龄:'))
        stu_num = next(self.__nums)
        # 创建学生对象
        stu = Student(stu_name, stu_age, stu_num)
        # 将学生添加到班级中
        self.students.append(stu)

    # 删除学生
    def del_student(self):
        del_name = input('删除学生的姓名:')
        for stu in self.students[:]:
            if stu.name == del_name:
                self.students.remove(stu)

    # 点名
    def call_the_roll(self):
        for stu in self.students:
            # 喊名字
            print(stu.name)
            # 如果在教室
            if stu.state:
                # 答到
                stu.amount()
            else:
                print('....')

    def average_age(self):
        sum1 = 0
        for stu in self.students:
            sum1 += stu.age
        average = sum1//len(self.students)
        print('平均年龄: %d' % average)
        return average

    def cl_show(self):
        for stu in self.students:
            stu.show()


class1 = Class('py1901')

print('=========添加学生===========')
# for _ in range(5):
class1.add_student()
class1.cl_show()
print('=========删除学生===========')
class1.del_student()
class1.cl_show()
print('=========点名===========')
class1.call_the_roll()
class1.average_age()