python os.rename(...)将无法正常工作！ [英] python os.rename(...) won't work !

问题描述

我正在编写一个Python函数，将文件列表的扩展名更改为另一个扩展名，例如将txt更改为rar，这只是一个闲置的示例.但是我遇到了一个错误.代码是:

I am writing a Python function to change the extension of a list of files into another extension, like txt into rar, that's just an idle example. But I'm getting an error. The code is:

import os
def dTask():
    #Get a file name list
    file_list = os.listdir('C:\Users\B\Desktop\sil\sil2')
    #Change the extensions
    for file_name in file_list:
        entry_pos = 0;
        #Filter the file name first for '.'
        for position in range(0, len(file_name)):
            if file_name[position] == '.':
                break
        new_file_name = file_name[0:position]
        #Filtering done !
        #Using the name filtered, add extension to that name
        new_file_name = new_file_name + '.rar'
        #rename the entry in the file list, using new file name
        print 'Expected change from: ', file_list[entry_pos]
        print 'into File name: ', new_file_name
        os.rename(file_list[entry_pos], new_file_name)
        ++entry_pos
Error:
>>> dTask()
Expected change from:  New Text Document (2).txt
into File name:  New Text Document (2).rar
Traceback (most recent call last):
  File "<pyshell#10>", line 1, in <module>
    dTask()
  File "C:\Users\B\Desktop\dTask.py", line 19, in dTask
    os.rename(file_list[entry_pos], new_file_name)
WindowsError: [Error 2] The system cannot find the file specified

如打印输出中所示，我可以成功获得可变级别的另一个扩展名的文件名，但实际上不行，因为我无法在OS级别结束此过程.错误来自os.rename(...).知道如何解决这个问题吗?

I can succeed in getting the file name with another extension in variable level as you can see in the print-out, but not in reality because I can not end this process in OS level. The error is coming from os.rename(...). Any idea how to fix this ?

推荐答案

1. 正如其他人所述，您要么需要提供这些文件的路径，要么切换当前工作目录，以便操作系统可以找到这些文件.

1. As the others have already stated, you either need to provide the path to those files or switch the current working directory so the os can find the files.

++entry_pos不执行任何操作. Python中没有增量运算符.前缀+恰好具有前缀-对称.用两个+前缀只是两个无操作.因此，您实际上并没有执行任何操作(将其更改为entry_pos += 1之后，您仍会在每次迭代中将其重置为零.

++entry_pos doesn't do anything. There is no increment operator in Python. Prefix + is just there fore symmetry with prefix -. Prefixing something with two + is just two no-ops. So you're not actually doing anything (and after you change it to entry_pos += 1, you're still resetting it to zero in each iteration.

此外，您的代码也非常笨拙-例如，您正在使用file_list的单独索引，即使仅使用该变量，也无法使其与迭代变量file_name保持同步！为了展示如何更好地做到这一点.

Also, your code is very inelegant - for example, you are using a separate index to file_list and fail to keep that in synch with the iteration variable file_name, even though you could just use that one! To show how this can be done better.

-

def rename_by_ext(to_ext, path):
    if to_ext[0] != '.':
        to_ext = '.'+to_ext
    print "Renaming files in", path
    for file_name in os.listdir(path):
        root, ext = os.path.splitext(file_name)
        print "Renaming", file_name, "to", root+ext
        os.rename(os.path.join(path, file_name), os.path.join(path, root+to_ext))
rename_by_ext('.rar', '...')

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