Python 基础：文件操作

5.1 文件读写

# 读取文件
with open("file.txt", "r", encoding="utf-8") as f:
    content = f.read()           # 读取全部
    # f.readline()             # 读取一行
    # f.readlines()            # 读取所有行到列表

# 写入文件
with open("output.txt", "w", encoding="utf-8") as f:
    f.write("Hello, World!\n")
    f.write("第二行")

# 追加模式
with open("log.txt", "a", encoding="utf-8") as f:
    f.write("新的日志内容\n")

5.2 JSON 操作

import json

# 写入 JSON
data = {"name": "Alice", "age": 25, "scores": [90, 85, 92]}
with open("data.json", "w", encoding="utf-8") as f:
    json.dump(data, f, ensure_ascii=False, indent=2)

# 读取 JSON
with open("data.json", "r", encoding="utf-8") as f:
    data = json.load(f)
    print(data["name"])  # Alice

# 字符串 ↔ JSON
json_str = json.dumps(data, ensure_ascii=False)
data2 = json.loads(json_str)

5.3 Pathlib（推荐方式）

from pathlib import Path

# 路径操作
p = Path(".") / "subdir" / "file.txt"
print(p)                # subdir/file.txt
print(p.parent)         # subdir
print(p.stem)           # file
print(p.suffix)         # .txt

# 读写文件
p.write_text("Hello", encoding="utf-8")
content = p.read_text(encoding="utf-8")

# 目录操作
Path("new_dir").mkdir(exist_ok=True)  # 创建目录
Path("old_dir").rmdir()               # 删除空目录

# 遍历目录
for f in Path(".").iterdir():
    print(f.name)

5.4 CSV 操作

import csv

# 写入 CSV
with open("data.csv", "w", encoding="utf-8", newline="") as f:
    writer = csv.DictWriter(f, fieldnames=["name", "age", "city"])
    writer.writeheader()
    writer.writerows([
        {"name": "Alice", "age": 25, "city": "Beijing"},
        {"name": "Bob", "age": 30, "city": "Shanghai"},
    ])

# 读取 CSV
with open("data.csv", "r", encoding="utf-8") as f:
    reader = csv.DictReader(f)
    for row in reader:
        print(row["name"], row["age"])

---

[[返回 Python 首页|python/index]]