### Python 小抄

• 类的写法

• 用法：f"{year}"

  1 2 3 4 5 6 7 8 9 10 11  class Car: def __init__(self, make, model, year): self.make = make self.model = model self.year = year self.odometer_reading = 0 def get_desc_name(self): long_name = f"{self.year} {self.make} {self.model}" return long_name.title() 

• 文件内容写到列表

• zfill，字符串右对齐，前面填充0

• 用法：“if birthday in pi_str”

  1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17  filename = 'pi_million_digits.txt' with open(filename) as file_object: lines = file_object.readlines() pi_str = '' for line in lines: pi_str += line.strip() for i in range(1, 32): birthday = '1805' birthday = birthday + str(i).zfill(2) if birthday in pi_str: print(f"{birthday} - yes") else: print(birthday) 

• json的用法

• 用法：ensure_ascii=False

  1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18  import json def count_words(filename): try: with open(filename, encoding='utf-8') as f: contents = f.read() except FileNotFoundError: print(f"Sorry, the file {filename} does not exist.") else: words = contents.split() num_words = len(words) return words[:10] filename = 'alice.txt' save_file = 'json.txt' with open(save_file, 'w', encoding='utf-8') as f: json.dump(count_words(filename), f, ensure_ascii=False)