实验7 面向对象编程与内置模块

task1.py

code:

class Account:
    def __init__(self,name,account_number,initial_amount = 10):
        self._name = name
        self._card_no = account_number
        self._balance = initial_amount
    def deposit(self,amount):
        self._balance += amount
    def withdraw(self,amount):
        if self._balance < amount:
            print('余额不足')
            return

        self._balance -= amount
    def info(self):
        print('持卡人姓名：',self._name)
        print('持卡人账号：',self._card_no)
        print('持卡人账户余额：',self._balance)
    
def main():
    print('测试账户1:'.center(30,'*'))
    a1 = Account('Bob','5006692',20000)
    a1.deposit(5000)
    a1.withdraw(4000)
    a1.info()

    print()

    print('测试账户2:'.center(30,'*'))
    a2 = Account('Joe','5006692',20000)
    a2.withdraw(10000)
    a2.withdraw(5000)
    a2.info()

if __name__ == '__main__':
    main()

output:

Understanding and Experiencing：

Account类共有 name、account_number和initial_amount这三个属性。其中我们所调用的是deposit和withdraw函数，其功能是在initial_amount中扣除或增加Balance。且程序还具有判断余额是否足够的功能。在编写代码def的时候没有注意main()的缩进导致无法调用main函数，因此在写代码时应要时刻注意缩进，利用tab键进行调试。

shape.py

code:

class Shape:
    def info(self):
        pass
    def area(self):
        pass
    def perimeter(self):
        pass
class Rect(Shape):
    def __init__(self, x=0 , y=0 ,length = 2,width = 1):
        self._x = x
        self._y = y
        self._width = width
        self._length = length
    def info(self):
        print(f'矩形左上角顶点坐标:({self._x},{self._y})')
        print(f'矩形长：{self._length}')
        print(f'矩形宽：{self._width}')
    def area(self):
        return self._length * self._width
    def perimeter(self):
        return (self._width+self._length)*2

class Circle(Shape):
    def __init__(self, x=0, y=0, radius=1):
        self._x = x
        self._y = y
        self._r = radius
    def info(self):
        print(f'圆心: ({self._x}, {self._y})')
        print(f'半径: {self._r}')
    def area(self):
        return 3.14 * self._r * self._r
    def perimeter(self):
        return 2 * 3.14 * self._r
class Triangle(Shape):
    def __init__(self, a=1, b=1, c=1):
        self._a, self._b, self._c = a, b, c
    def info(self):
        print(f'三角形三边长: ({self._a}, {self._b}, {self._c})')
    def area(self):
        s = (self._a + self._b + self._c) / 2
        ans = (s * (s - self._a) * (s - self._b) * (s - self._c)) ** 0.5
        return ans
    def perimeter(self):
        return (self._a + self._b + self._c)
# 测试类
def main():
    print('测试1：'.center(40, '*'))
    shapes_lst1 = [Circle(), Rect(), Triangle()]
    for t in shapes_lst1:
        t.info()
        print(f'面积: {t.area():.2f}')
        print(f'周长: {t.perimeter():.2f}')
        print()
    print('测试2：'.center(40, '*'))
    shapes_lst2 = [Circle(x=2, y=2, radius=10),
                   Rect(x=50, y=50, length=10, width=5),
                   Triangle(a=3, b=4, c=5)]
    for t in shapes_lst2:
        t.info()
        print(f'面积: {t.area():.2f}')
        print(f'周长: {t.perimeter():.2f}')
        print()
if __name__ == '__main__':
    main()

output:

task2.py

code:

from shape import Rect, Circle
shape_lst = [Rect(5, 5, 10, 5), Circle(), Circle(1, 1, 10)]
for i in shape_lst:
    i.info()
    print(f'面积: {i.area(): .2f}')
    print(f'周长: {i.perimeter(): .2f}')
    print()

output:

Understanding and Experiencing：

在编写该代码时，学生遇到了以下报错：TypeError: Rect() takes no arguments，在不断的调整重复中程序始终报错，并随着修改报错类型也在不断变化。最终学生发现错误的来源为line9中

    def __init__(self, x=0 , y=0 ,length = 2,width = 1):
被写成了：

    def __int__(self, x=0 , y=0 ,length = 2,width = 1):
仅一个小小字符之差，给我带来了半个小时的困扰和迷惑！绝不是代码过于矫情，本身在pycharm的环境下纠错分类已经足够简单，更别提更加复杂的环境！事无巨细。

task3.py

code:

from math import *
k = 1
for i in range(5):
    for (m, s, x) in [(0, 2, k)]:
        fx = (1 / (sqrt(2 * pi )*s)) * exp((-1 / 2) * ((x - m) / s) ** 2)
        print(f'x = {k}',',',f'f={"%.8f" %fx}')
    k += 2

output: