Python读写txt文件的多种方法

# 打开文件进行写入（如果文件不存在会自动创建）
with open('example.txt', 'w', encoding='utf-8') as file:
    file.write("这是第一行文本\n")
    file.write("这是第二行文本\n")
    file.write("这是第三行文本\n")

lines = ["第一行\n", "第二行\n", "第三行\n"]

with open('multiline.txt', 'w', encoding='utf-8') as file:
    file.writelines(lines)

with open('example.txt', 'a', encoding='utf-8') as file:
    file.write("这是追加的内容\n")

name = "张三"
age = 25

with open('formatted.txt', 'w', encoding='utf-8') as file:
    file.write(f"姓名: {name}, 年龄: {age}\n")
    # 或者使用format
    file.write("职业: {}\n".format("工程师"))

with open('example.txt', 'r', encoding='utf-8') as file:
    content = file.read()
    print(content)

with open('example.txt', 'r', encoding='utf-8') as file:
    for line in file:  # 迭代器方式逐行读取
        print(line.strip())  # strip()去除行尾换行符

with open('example.txt', 'r', encoding='utf-8') as file:
    lines = file.readlines()  # 返回包含所有行的列表
    for i, line in enumerate(lines, 1):
        print(f"第{i}行: {line.strip()}")

# 方法1：逐行读取（内存友好）
with open('large_file.txt', 'r', encoding='utf-8') as file:
    for line in file:
        process_line(line)  # 处理每一行的函数

# 方法2：分块读取
chunk_size = 1024 * 1024  # 1MB
with open('large_file.txt', 'r', encoding='utf-8') as file:
    while True:
        chunk = file.read(chunk_size)
        if not chunk:
            break
        process_chunk(chunk)  # 处理每个块的函数

# 相对路径（相对于当前工作目录）
with open('./data/example.txt', 'r') as file:
    ...

# 绝对路径（推荐使用os.path或pathlib处理跨平台路径）
import os
file_path = os.path.join('C:', 'Users', 'username', 'Documents', 'example.txt')
with open(file_path, 'r') as file:
    ...

from pathlib import Path

# 创建Path对象
file_path = Path('data/example.txt')

# 检查文件是否存在
if file_path.exists():
    # 读取文件
    content = file_path.read_text(encoding='utf-8')
    print(content)
    
    # 写入文件
    file_path.write_text("新内容\n", encoding='utf-8')

# 尝试常见编码
encodings = ['utf-8', 'gbk', 'gb2312', 'big5', 'latin1']

def read_with_fallback(filename):
    for encoding in encodings:
        try:
            with open(filename, 'r', encoding=encoding) as file:
                return file.read()
        except UnicodeDecodeError:
            continue
    raise UnicodeDecodeError(f"无法解码文件 {filename}，尝试了所有常见编码")

# 写入时忽略无法编码的字符（不推荐，除非必要）
with open('output.txt', 'w', encoding='utf-8', errors='ignore') as file:
    file.write("包含特殊字符的文本")

with open('example.txt', 'r+', encoding='utf-8') as file:
    content = file.read()
    file.seek(0)  # 移动指针到文件开头
    file.write("新内容\n" + content)  # 在开头插入内容

import csv

# 写入CSV格式文本
with open('data.txt', 'w', newline='', encoding='utf-8') as file:
    writer = csv.writer(file)
    writer.writerow(['姓名', '年龄', '城市'])
    writer.writerow(['张三', 25, '北京'])
    writer.writerow(['李四', 30, '上海'])

# 读取CSV格式文本
with open('data.txt', 'r', encoding='utf-8') as file:
    reader = csv.reader(file)
    for row in reader:
        print(row)

import json

data = {
    "name": "张三",
    "age": 25,
    "skills": ["Python", "数据分析"]
}

# 写入JSON
with open('data.txt', 'w', encoding='utf-8') as file:
    json.dump(data, file, ensure_ascii=False, indent=4)

# 读取JSON
with open('data.txt', 'r', encoding='utf-8') as file:
    loaded_data = json.load(file)
    print(loaded_data)

from pathlib import Path

def process_file_operations():
    # 创建目录（如果不存在）
    data_dir = Path('data')
    data_dir.mkdir(exist_ok=True)
    
    # 写入文件
    file_path = data_dir / 'example.txt'
    file_path.write_text(
        "第一行文本\n"
        "第二行文本\n"
        "第三行文本\n",
        encoding='utf-8'
    )
    
    # 读取并处理文件
    if file_path.exists():
        content = file_path.read_text(encoding='utf-8')
        print("文件内容:")
        print(content)
        
        # 追加内容
        file_path.write_text(
            content + "\n这是追加的内容\n",
            encoding='utf-8'
        )
    else:
        print("文件不存在")

if __name__ == "__main__":
    process_file_operations()