python修改文件的三种方式

方式一:原文件修改


def change_file(file,old_str,new_str):
    """
    param file:文件名
    param old_str:旧字符串
    param new_str:新字符串
    """
    file_data = ""
    with open(file, "r", encoding="utf-8") as f:
        for line in f:
            if old_str in line:
                line = line.replace(old_str,new_str)
            file_data += line
    with open(file,"w",encoding="utf-8") as f:
        f.write(file_data)
 
change_file("filename", "12345", "xxxxx")

方式二:新文件替换

import os
def change_file(file,old_str,new_str):
    """
    将替换的字符串写到一个新的文件中,然后将原文件删除,新文件改为原来文件的名字
    :param file: 文件路径
    :param old_str: 需要替换的字符串
    :param new_str: 替换的字符串
    :return: None
    """
    with open(file, "r", encoding="utf-8") as f1,open("%s.bak" % file, "w", encoding="utf-8") as f2:
        for line in f1:
            if old_str in line:
                line = line.replace(old_str, new_str)
            f2.write(line)
    os.remove(file)
    os.rename("%s.bak" % file, file)
 
chnage_file("filename", "12345", "xxxxx")

方式三:正则(属于第二种方式)

import re,os
def change_file(file,old_str,new_str):
    with open(file, "r", encoding="utf-8") as f1,open("%s.bak" % file, "w", encoding="utf-8") as f2:
        for line in f1:
            f2.write(re.sub(old_str,new_str,line))
    os.remove(file)
    os.rename("%s.bak" % file, file)
change_file("filename", "12345", "xxxxx")

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