挑战Python100题(6)

100+ Python challenging programming exercises 6

Question 51

Define a class named American and its subclass NewYorker.

Hints: Use class Subclass(ParentClass) to define a subclass.

定义一个名为American的类及其子类NewYorker。

提示：使用class Subclass（ParentClass）来定义子类。

Solution:

class American:  def __init__(self, name, age):  self.name = name  self.age = age  def introduce(self):  return f"Hello, my name is {self.name} and I am {self.age} years old."  class NewYorker(American):  def introduce(self):  return f"Yo, my name is {self.name} and I am from New York. I'm {self.age} years old."anAmerican = American('Tom',8)
aNewYorker = NewYorker('Jerry',5)print(anAmerican.introduce())
print(aNewYorker.introduce())

Out:

Hello, my name is Tom and I am 8 years old.
Yo, my name is Jerry and I am from New York. I'm 5 years old.

Question 52

Define a class named Circle which can be constructed by a radius. The Circle class has a method which can compute the area.

Hints: Use def methodName(self) to define a method.

定义一个名为“圆”的类，该类可以由半径构造。Circle类有一个可以计算圆面积的方法。

提示：使用def methodName(self)定义方法。

Solution:

class Circle(object):def __init__(self, r):self.radius = rdef area(self):return self.radius**2*3.14aCircle = Circle(10)
print(aCircle.area())

Out:

314.0

Question 53

Define a class named Rectangle which can be constructed by a length and width. The Rectangle class has a method which can compute the area.

Hints: Use def methodName(self) to define a method.

定义一个名为Rectangle的类，该类可以由长度和宽度构造。Rectangle类有一个可以计算面积的方法。
提示：使用def methodName(self)定义方法。

Solution:

class Rectangle(object):def __init__(self, l, w):self.length = lself.width = wdef area(self):return self.length*self.widthaRectangle = Rectangle(3,5)
print(aRectangle.area())

Out:

Question 54

Define a class named Shape and its subclass Square. The Square class has an init function which takes a length as argument. Both classes have a area function which can print the area of the shape where Shape's area is 0 by default.

Hints: To override a method in super class, we can define a method with the same name in the super class.

定义一个名为Shape的类及其子类Square。Square类有一个init函数，它以一个长度作为参数。这两个类都有一个面积函数，该函数可以打印形状的面积，其中shape的面积默认为0。

提示：要覆盖SuperClass中的方法，可以在SuperClass中定义一个同名的方法。

Solution:

class Shape(object):def __init__(self):passdef area(self):return 0class Square(Shape):def __init__(self, l):Shape.__init__(self)self.length = ldef area(self):return self.length*self.lengthaSquare = Square(3)
print(aSquare.area())

Out:

Question 55

Please raise a RuntimeError exception.

Hints: Use raise() to raise an exception.

请引发RuntimeError异常。

提示：使用raise()引发异常。

Solution:

raise RuntimeError('something wrong')

Question 56

Write a function to compute 5/0 and use try/except to catch the exceptions.

Hints: Use try/except to catch exceptions.

编写一个函数来计算5/0，并使用try/except来捕获异常。

提示：使用try/except捕获异常。

Solution:

def throws():return 5/0try:throws()
except ZeroDivisionError:print("division by zero!")
except Exception(err):print('Caught an exception')
finally:print('In finally block for cleanup')

Out:

division by zero!
In finally block for cleanup

Question 57

Define a custom exception class which takes a string message as attribute.

Hints: To define a custom exception, we need to define a class inherited from Exception.

定义一个以字符串消息为属性的自定义异常类。

提示：要定义自定义异常，我们需要定义从exception继承的类。

Solution:

class CustomException(Exception):  def __init__(self, message):  self.message = messagetry:  raise CustomException("This is a custom exception")  
except CustomException as e:  print(e.message)

Out:

"This is a custom exception"

Question 58

Assuming that we have some email addresses in the "username@companyname.com" format, please write program to print the user name of a given email address. Both user names and company names are composed of letters only.

Example: If the following email address is given as input to the program:

john@google.com

Then, the output of the program should be:

john

In case of input data being supplied to the question, it should be assumed to be a console input.

Hints: Use \w to match letters.

假设我们在“username@companyname.com“格式，请编写程序打印给定电子邮件地址的用户名。用户名和公司名称都只能由字母组成。

Solution:

import re
emailAddress = input()
pat2 = "(\w+)@"
r2 = re.match(pat2,emailAddress)
print(r2.group(1))

In:
john@google.com

Out:
John

Question 59

Assuming that we have some email addresses in the "username@companyname.com" format, please write program to print the company name of a given email address. Both user names and company names are composed of letters only.

Example: If the following email address is given as input to the program:

john@google.com

Then, the output of the program should be:

google

In case of input data being supplied to the question, it should be assumed to be a console input.

Hints: Use \w to match letters.

假设我们在“username@companyname.com“格式，请编写程序打印给定电子邮件地址的公司名称。用户名和公司名称都只能由字母组成。

Solution:

import re
emailAddress = input()
pat2 = "(\w+)@(\w+)\.(com)"
r2 = re.match(pat2,emailAddress)
print(r2.group(2))

In:
john@google.com

Out:
google

Question 60

Write a program which accepts a sequence of words separated by whitespace as input to print the words composed of digits only.

Example: If the following words is given as input to the program:

2 cats and 3 dogs.

Then, the output of the program should be:

['2', '3']

In case of input data being supplied to the question, it should be assumed to be a console input.

Hints: Use re.findall() to find all substring using regex.

编写一个程序，接受由空格分隔的单词序列作为输入，只打印由数字组成的单词。

示例：如果将以下单词作为程序的输入：

2只猫和3只狗。

然后，程序的输出应该是：

['2'，'3']

在向问题提供输入数据的情况下，应假设它是控制台输入。

提示：使用re.findall()使用正则表达式查找所有子字符串。

Solution:

import re
s = input()
print(re.findall("\d+",s))

In:
2 cats and 3 dogs

Out:
['2', '3']

来源：GitHub - 965714601/Python-programming-exercises: 100+ Python challenging programming exercises