Python文件和异常处理小结

with open('pi_digits.txt', 'r') as file:
    contents = file.read()
print(contents)

with open('pi_digits.txt') as file:
    lines = file.readlines()  # 将各行存入列表
for line in lines:
    print(line.strip())       # 去除每行末尾的换行符

with open('big_file.txt') as file:
    for line in file:
        process(line)  # 每次处理一行，内存友好

with open('output.txt', 'w') as file:
    file.write("Hello, World!")

with open('output.txt', 'a') as file:
    file.write("\nAppended line.")

with open('output.txt', 'a') as file:
    file.write("\nAppended line.")

filename = 'missing.txt'
try:
    with open(filename) as file:
        content = file.read()
except FileNotFoundError:
    print(f"文件 {filename} 不存在！")

try:
    # 可能出错的代码
except FileNotFoundError:
    pass  # 静默处理

import json
data = {'name': 'Alice', 'age': 30}
with open('data.json', 'w') as file:
    json.dump(data, file)  # 写入文件
# 读取JSON数据
with open('data.json') as file:
    loaded_data = json.load(file)
print(loaded_data['name'])  # 输出：Alice

def save_user_data(username):
    """保存用户数据到JSON文件"""
    with open('users.json', 'w') as file:
        json.dump({'username': username}, file)