python 修改文件内容3种方法

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一、修改原文件方式

 def alter(file,old_str,new_str):
     """
     替换文件中的字符串
     :param file:文件名
     :param old_str:就字符串
     :param new_str:新字符串
     :return:
     """
      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)
 
 alter("file1", "09876", "python")

二、把原文件内容和要修改的内容写到新文件中进行存储的方式

2.1 python字符串替换的方法，修改文件内容

import os
def alter(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)

alter("file1", "python", "测试")

2.2 python 使用正则表达式 替换文件内容 re.sub 方法替换

 import re,os
 def alter(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)
 alter("file1", "admin", "password")