4、文件的改：

4、文件的改：

        1、打开原文件old_file，将原内容读取到内存

        2、创建一个新文件new_file

        3、将原内容通过你改写成新内容，写入到新文件

        4、将原文件删除

        5、将新文件重命名成原文件

       

        方法一，原文件内容不大，可以用此方法，但是此方法还是很low。

                 import os

                 with open('change', encoding='utf-8') as f1,\

                         open('change1',encoding='utf-8', mode='w') as f2:

                         old_content = f1.read()

                         new_content = old_content.replace('alex', 'SB')

                         f2.write(new_content)

                 os.remove('change')

                 os.rename('change1', 'change')

       

        方法二

                 with open('change', encoding='utf-8') as f1,\

                         open('change1',encoding='utf-8', mode='w') as f2:

                         for line in f1:

                                  new_line = line.replace('SB', 'alex')

                                  f2.write(new_line)

                 os.remove('change')

                 os.rename('change1', 'change')