python 修改文件

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")

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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

import osdef 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:

        forlinein f1:

            ifold_strin 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")

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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")