如何在多个.txt文件中将行的特定第一个字符替换为其他字符？(Python)

import os

def replace_first_char(file_path, old_char, new_char):
    """
    替换指定文件中每行的第一个字符
    :param file_path: 文件路径
    :param old_char: 需要被替换的字符
    :param new_char: 替换后的字符
    """
    # 读取文件内容并替换每行的第一个字符
    with open(file_path, 'r', encoding='utf-8') as file:
        lines = file.readlines()
    
    new_lines = [new_char + line[1:] if line and line[0] == old_char else line for line in lines]
    
    # 将替换后的内容写回文件
    with open(file_path, 'w', encoding='utf-8') as file:
        file.writelines(new_lines)

def process_directory(directory, old_char, new_char):
    """
    处理目录中的所有 .txt 文件
    :param directory: 目录路径
    :param old_char: 需要被替换的字符
    :param new_char: 替换后的字符
    """
    for root, _, files in os.walk(directory):
        for file in files:
            if file.endswith('.txt'):
                file_path = os.path.join(root, file)
                replace_first_char(file_path, old_char, new_char)

# 示例用法
directory_path = 'path/to/your/directory'  # 替换为你的目录路径
old_character = 'a'  # 需要被替换的字符
new_character = 'b'  # 替换后的字符

process_directory(directory_path, old_character, new_character)