s = "Hello, World!"

reversed_s = s[::-1]

print(reversed_s)

8. 检查回文

def is_palindrome(s):

return s == s[::-1]

print(is_palindrome("racecar"))

9. 计算阶乘

def factorial(n):

if n == 0:

return 1

return n * factorial(n - 1)

print(factorial(5))

10. 找到列表中的最大值和最小值

numbers = [1, 2, 3, 4, 5]

max_value = max(numbers)

min_value = min(numbers)

print(max_value, min_value)

11. 列表去重

numbers = [1, 2, 2, 3, 4, 4, 5]

unique_numbers = list(set(numbers))

print(unique_numbers)

12. 字符串中单词计数

s = "hello world hello"

word_count = { }

for word in s.split():

word_count[word] = word_count.get(word, 0) + 1

print(word_count)

13. 合并两个字典

dict1 = { 'a': 1, 'b': 2}

dict2 = { 'b': 3, 'c': 4}

merged_dict = { **dict1, **dict2}

print(merged_dict)

14. 计算两个日期之间的天数

from datetime import datetime

date1 = datetime(2022, 1, 1)

date2 = datetime(2022, 12, 31)

days_difference = (date2 - date1).days

print(days_difference)

15. 生成列表的所有排列

import itertools

numbers = [1, 2, 3]

permutations = list(itertools.permutations(numbers))

print(permutations)

16. 读取文件内容

with open('file.txt', 'r') as file:

content = file.read()

print(content)

17. 写入文件

with open('file.txt', 'w') as file:

file.write("Hello, World!")

18. 发送HTTP请求

import requests

response = requests.get('https://api.github.com')

print(response.json())

19. 创建一个类和对象

class Dog:

def __init__(self, name):

self.name = name

def bark(self):

print(f'{ self.name} says woof!')

my_dog = Dog('Rex')

my_dog.bark()

20. 异常处理

try:

result = 10 / 0

except ZeroDivisionError:

print("Cannot divide by zero")

21. Lambda函数

add = lambda x, y: x + y

print(add(2, 3))

22. 列表推导式

squares = [x**2 for x in range(10)]

print(squares)

23. 字典推导式

squares = { x: x**2 for x in range(10)}

print(squares)

24. 过滤列表中的偶数

numbers = [1, 2, 3, 4, 5, 6]

even_numbers = [x for x in numbers if x % 2 == 0]

print(even_numbers)

25. 计算字符串的长度

s = "Hello, World!"

length = len(s)

print(length)

26. 使用装饰器

def my_decorator(func):

def wrapper():

print("Something is happening before the function is called.")

func()

print("Something is happening after the function is called.")

return wrapper

@my_decorator

def say_hello():

print("Hello!")

say_hello()

27. 生成随机密码

import string

import random

def generate_password(length):

characters = string.ascii_letters + string.digits + string.punctuation

return ''.join(random.choice(characters) for i in range(length))

print(generate_password(12))

28. 使用Counter统计元素频率

from collections import Counter

data = ['a', 'b', 'c', 'a', 'b', 'b']

counter = Counter(data)

print(counter)

29. 合并多个列表

list1 = [1, 2, 3]

list2 = [4, 5, 6]

merged_list = list1 + list2

print(merged_list)

30. 获取当前日期和时间

from datetime import datetime

now = datetime.now()

print(now)

31. 将字符串转换为日期

from datetime import datetime

date_string = "2023-01-01"

date_object = datetime.strptime(date_string, '%Y-%m-%d')

print(date_object)

32. 计算两点之间的距离

import math

def distance(x1, y1, x2, y2):

return math.sqrt((x2 - x1)**2 + (y2 - y1)**2)

print(distance(0, 0, 3, 4))

33. 检查文件是否存在

import os

file_exists = os.path.exists('file.txt')

print(file_exists)

34. 获取文件大小

file_size = os.path.getsize('file.txt')

print(file_size)

35. 压缩文件

import zipfile

with zipfile.ZipFile('archive.zip', 'w') as zipf:

zipf.write('file.txt')

36. 解压文件

with zipfile.ZipFile('archive.zip', 'r') as zipf:

zipf.extractall('extracted')

37. 计时器

import time

start_time = time.time()

# Some code to time

end_time = time.time()

print(f"Execution time: { end_time - start_time} seconds")

38. 多线程

import threading

def print_numbers():

for i in range(5):

print(i)

thread = threading.Thread(target=print_numbers)

thread.start()

thread.join()

39. 读取JSON文件

import json

with open('data.json', 'r') as file:

data = json.load(file)

print(data)

40. 写入JSON文件

data = { 'name': 'John', 'age': 30}

with open('data.json', 'w') as file:

json.dump(data, file)

41. 计算字符串的哈希值

import hashlib

s = "Hello, World!"

hash_object = hashlib.sha256(s.encode())

hash_hex = hash_object.hexdigest()

print(hash_hex)

42. 检查列表是否为空

numbers = []

is_empty = not numbers

print(is_empty)

43. 生成当前时间的时间戳

import time

timestamp = time.time()

print(timestamp)

44. 延迟执行

import time

```python

time.sleep(5) # 延迟5秒

print("5 seconds have passed")

45. 使用正则表达式匹配字符串

import re

pattern = r'\d+'

s = "The number is 12345"

matches = re.findall(pattern, s)

print(matches)

46. 检查字符串是否包含子字符串

s = "Hello, World!"

contains = "World" in s

print(contains)

47. 列出目录中的所有文件

import os

files = os.listdir('.')

print(files)

48. 获取环境变量

import os

home_directory = os.getenv('HOME')

print(home_directory)

49. 执行外部命令

import subprocess

result = subprocess.run(['ls', '-l'], stdout=subprocess.PIPE)

print(result.stdout.decode())

50. 将数据写入CSV文件

import csv

data = [

['Name', 'Age', 'City'],

['Alice', 30, 'New York'],

['Bob', 25, 'San Francisco']

]

with open('people.csv', 'w', newline='') as file:code>

writer = csv.writer(file)

writer.writerows(data)

总结