entityMap|blocks|key|6nd1f|text|在"+write“模式下打开一个文件会清除它，你不需要特别写它：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|dh65r|open("filename",+"w").close()|code-block|syntax|javascript|bor9t|(您应该关闭它，因为文件自动关闭的时间可能是特定于实现的)^0|0|0^^$0|$]|1|@$2|3|4|5|6|7|8|J|9|@]|A|@]|B|$]]|$2|C|4|D|6|E|8|K|9|@]|A|@]|B|$F|G]]|$2|H|4|I|6|7|8|L|9|@]|A|@]|B|$]]]]

Opening a file in "write" mode clears it, you don't specifically have to write to it:

<pre><code>open("filename", "w").close()
</code></pre>

(you should close it as the timing of when the file gets closed automatically may be implementation specific)

entityMap|blocks|key|e9qel|text|不是一个完整的答案，更像是ondra答案的延伸|type|unstyled|depth|inlineStyleRanges|entityRanges|data|efmsl|当使用|7tqrv|(我首选的方法)确保光标位于所需的位置。当打开要读取的新文件时-|70vpi|默认情况下，它的光标位置为0。但是，如果您已经在代码中解析了文件，请确保再次指向文件的开头，即|jvfa|默认情况下|bt3j9|从当前错误位置开始截断文件的内容。|bnc0h|一个简单的例子^0|0|0|0|0|0|0^^$0|$]|1|@$2|3|4|5|6|7|8|O|9|@]|A|@]|B|$]]|$2|C|4|D|6|7|8|P|9|@]|A|@]|B|$]]|$2|E|4|F|6|7|8|Q|9|@]|A|@]|B|$]]|$2|G|4|H|6|7|8|R|9|@]|A|@]|B|$]]|$2|I|4|J|6|7|8|S|9|@]|A|@]|B|$]]|$2|K|4|L|6|7|8|T|9|@]|A|@]|B|$]]|$2|M|4|N|6|7|8|U|9|@]|A|@]|B|$]]]]

Not a complete answer more of an extension to ondra's answer

When using <code>truncate()</code> ( my preferred method ) make sure your cursor is at the required position.
When a new file is opened for reading - <code>open('FILE_NAME','r')</code> it's cursor is at 0 by default.
But if you have parsed the file within your code, make sure to point at the beginning of the file again i.e <code>truncate(0)</code>
By default <code>truncate()</code> truncates the contents of a file starting from the current cusror position.

<a href="http://www.tutorialspoint.com/python/file_truncate.htm">A simple example</a>

entityMap|blocks|key|dfmru|text|来自user+@jamylak的另一种形式|type|unstyled|depth|inlineStyleRanges|entityRanges|data|5onoe|是|defms|with+open('filename.txt','w'):+pass|code-block|syntax|javascript^0|0|0^^$0|$]|1|@$2|3|4|5|6|7|8|J|9|@]|A|@]|B|$]]|$2|C|4|D|6|7|8|K|9|@]|A|@]|B|$]]|$2|E|4|F|6|G|8|L|9|@]|A|@]|B|$H|I]]]]

As @jamylak suggested, a good alternative that includes the <a href="https://stackoverflow.com/questions/3012488/what-is-the-python-with-statement-designed-for">benefits of context managers</a> is:
<pre><code>with open('filename.txt', 'w'):
 pass
</code></pre>

entityMap|blocks|key|8d46f|text|当使用|type|unstyled|depth|inlineStyleRanges|entityRanges|data|8d2mr|，我得到了奇怪的零|548pt|，特别是因为我是先读取文件的。要让它正常工作，我必须首先更改|277vk|添加到文件的开头|cismt|..。然后我就可以|d7qml|若要清除该文件，请执行以下操作。^0|0|0|0|0|0^^$0|$]|1|@$2|3|4|5|6|7|8|M|9|@]|A|@]|B|$]]|$2|C|4|D|6|7|8|N|9|@]|A|@]|B|$]]|$2|E|4|F|6|7|8|O|9|@]|A|@]|B|$]]|$2|G|4|H|6|7|8|P|9|@]|A|@]|B|$]]|$2|I|4|J|6|7|8|Q|9|@]|A|@]|B|$]]|$2|K|4|L|6|7|8|R|9|@]|A|@]|B|$]]]]

When using <code>with open("myfile.txt", "r+") as my_file:</code>, I get strange zeros in <code>myfile.txt</code>, especially since I am reading the file first. For it to work, I had to first change the pointer of <code>my_file</code> to the beginning of the file with <code>my_file.seek(0)</code>. Then I could do <code>my_file.truncate()</code> to clear the file.

entityMap|blocks|key|3at8u|text|您必须覆盖该文件。在C%2B%2B中：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|8q0m1|#include+

std::ofstream("test.txt",+std::ios::out).close();|code-block|syntax|javascript^0|0^^$0|$]|1|@$2|3|4|5|6|7|8|H|9|@]|A|@]|B|$]]|$2|C|4|D|6|E|8|I|9|@]|A|@]|B|$F|G]]]]

You have to overwrite the file. In C++:

<pre><code>#include &lt;fstream&gt;

std::ofstream("test.txt", std::ios::out).close();
</code></pre>

entityMap|blocks|key|a70pv|text|如果安全性对您很重要，那么打开文件以进行写入并再次关闭它是不够的。至少一些信息仍将在存储设备上，并且可以例如通过使用盘恢复实用程序来找到。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|frii8|例如，假设您要擦除的文件包含生产密码，并且需要在当前操作完成后立即删除。|58jnc|使用完文件后，零填充有助于确保敏感信息被销毁。|7k7fg|在最近的一个项目中，我们使用了以下代码，它适用于小的文本文件。它用零行覆盖现有的内容。|vt5s|import+os

def+destroy_password_file(password_filename):
++++with+open(password_filename)+as+password_file:
++++++++text+=+password_file.read()
++++lentext+=+len(text)
++++zero_fill_line_length+=+40
++++zero_fill+=+['0'+*+zero_fill_line_length
++++++++++++++++++++++for+_
++++++++++++++++++++++in+range(lentext+//+zero_fill_line_length+%2B+1)]
++++zero_fill+=+os.linesep.join(zero_fill)
++++with+open(password_filename,+'w')+as+password_file:
++++++++password_file.write(zero_fill)|code-block|syntax|javascript|65qt0|请注意，填零并不能保证您的安全。如果你真的很担心，你最好填零|c3sp1|和|a8c4i|使用像这样的专业实用程序|9enq2|文件切碎器|n3n3|或者|ae4mr|CCleaner|9uqvv|要清除驱动器上的“空白”空间，请执行以下操作。^0|0|0|0|0|0|0|0|0|0|0|0^^$0|$]|1|@$2|3|4|5|6|7|8|11|9|@]|A|@]|B|$]]|$2|C|4|D|6|7|8|12|9|@]|A|@]|B|$]]|$2|E|4|F|6|7|8|13|9|@]|A|@]|B|$]]|$2|G|4|H|6|7|8|14|9|@]|A|@]|B|$]]|$2|I|4|J|6|K|8|15|9|@]|A|@]|B|$L|M]]|$2|N|4|O|6|7|8|16|9|@]|A|@]|B|$]]|$2|P|4|Q|6|7|8|17|9|@]|A|@]|B|$]]|$2|R|4|S|6|7|8|18|9|@]|A|@]|B|$]]|$2|T|4|U|6|7|8|19|9|@]|A|@]|B|$]]|$2|V|4|W|6|7|8|1A|9|@]|A|@]|B|$]]|$2|X|4|Y|6|7|8|1B|9|@]|A|@]|B|$]]|$2|Z|4|10|6|7|8|1C|9|@]|A|@]|B|$]]]]

If security is important to you then opening the file for writing and closing it again will not be enough. At least some of the information will still be on the storage device and could be found, for example, by using a disc recovery utility.

Suppose, for example, the file you're erasing contains production passwords and needs to be deleted immediately after the present operation is complete.

Zero-filling the file once you've finished using it helps ensure the sensitive information is destroyed.

On a recent project we used the following code, which works well for small text files. It overwrites the existing contents with lines of zeros.

<pre><code>import os

def destroy_password_file(password_filename):
 with open(password_filename) as password_file:
 text = password_file.read()
 lentext = len(text)
 zero_fill_line_length = 40
 zero_fill = ['0' * zero_fill_line_length
 for _
 in range(lentext // zero_fill_line_length + 1)]
 zero_fill = os.linesep.join(zero_fill)
 with open(password_filename, 'w') as password_file:
 password_file.write(zero_fill)
</code></pre>

Note that zero-filling will not guarantee your security. If you're really concerned, you'd be best to zero-fill and use a specialist utility like <a href="http://www.fileshredder.org/" rel="nofollow noreferrer">File Shredder</a> or <a href="https://www.ccleaner.com/ccleaner" rel="nofollow noreferrer">CCleaner</a> to wipe clean the 'empty' space on your drive.

entityMap|blocks|key|465vt|text|你也可以使用这个(基于上面的几个答案)：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2chv6|file+=+open('filename.txt',+'w')
file.close()|code-block|syntax|javascript|a3ebu|当然，这是一种非常糟糕的清除文件的方法，因为它需要很多行代码，但我写这篇文章只是为了向您展示，在这个方法中也可以做到这一点。|cak25|编码快乐！^0|0|0|0^^$0|$]|1|@$2|3|4|5|6|7|8|L|9|@]|A|@]|B|$]]|$2|C|4|D|6|E|8|M|9|@]|A|@]|B|$F|G]]|$2|H|4|I|6|7|8|N|9|@]|A|@]|B|$]]|$2|J|4|K|6|7|8|O|9|@]|A|@]|B|$]]]]

You can also use this (based on a few of the above answers):
<pre><code>file = open('filename.txt', 'w')
file.close()
</code></pre>
of course this is a really bad way to clear a file because it requires so many lines of code, but I just wrote this to show you that it can be done in this method too.
happy coding!

entityMap|blocks|key|dejcv|text|由于文本文件是连续的，您不能直接擦除其中的数据。您可以选择：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|81gnb|最常见的方法是创建一个新文件。从原始文件中读取，并在新文件中写入除要擦除的部分以外的所有内容。写入所有文件后，删除旧文件并重命名新文件，使其具有原始名称。|ao5fq|您还可以从想要更改的位置开始截断和重写整个文件。寻找你想要更改的点，并将文件的其余部分读取到内存中。找回相同的点，截断文件，并写回内容，但不包括要擦除的部分。|4pq6m|另一个简单的选择是用相同长度的另一个数据覆盖数据。为此，寻找准确的位置并写入新数据。限制是它必须具有完全相同的长度。|742lh|看看|cjvu8|/|3v7fa|函数/方法来实现上面的任何想法。Python和C都有这些函数。^0|0|0|0|0|0|0^^$0|$]|1|@$2|3|4|5|6|7|8|O|9|@]|A|@]|B|$]]|$2|C|4|D|6|7|8|P|9|@]|A|@]|B|$]]|$2|E|4|F|6|7|8|Q|9|@]|A|@]|B|$]]|$2|G|4|H|6|7|8|R|9|@]|A|@]|B|$]]|$2|I|4|J|6|7|8|S|9|@]|A|@]|B|$]]|$2|K|4|L|6|7|8|T|9|@]|A|@]|B|$]]|$2|M|4|N|6|7|8|U|9|@]|A|@]|B|$]]]]

Since text files are sequential, you can't directly erase data on them. Your options are:

<ul>
<li>The most common way is to create a new file. Read from the original file and write everything on the new file, except the part you want to erase. When all the file has been written, delete the old file and rename the new file so it has the original name.</li>
<li>You can also truncate and rewrite the entire file from the point you want to change onwards. Seek to point you want to change, and read the rest of file to memory. Seek back to the same point, truncate the file, and write back the contents without the part you want to erase.</li>
<li>Another simple option is to overwrite the data with another data of same length. For that, seek to the exact position and write the new data. The limitation is that it must have exact same length.</li>
</ul>

Look at the <code>seek</code>/<code>truncate</code> function/method to implement any of the ideas above. Both Python and C have those functions.

entityMap|blocks|key|e62gv|text|除非需要擦除文件的末尾，否则不能从文件中就地“擦除”。要么满足于覆盖“空”值，要么读取文件中您关心的部分并将其写入另一个文件。|type|unstyled|depth|inlineStyleRanges|entityRanges|data^0^^$0|$]|1|@$2|3|4|5|6|7|8|C|9|@]|A|@]|B|$]]]]

You cannot "erase" from a file in-place unless you need to erase the end. Either be content with an overwrite of an "empty" value, or read the parts of the file you care about and write it to another file.

entityMap|blocks|key|fdvdo|text|在你的程序中将文件指针赋值为null将会消除对文件的引用。文件还在那里。我认为|type|unstyled|depth|inlineStyleRanges|entityRanges|data|e513p|中的函数。|d49hv|就是你要找的东西。对Python不太确定。^0|0|0^^$0|$]|1|@$2|3|4|5|6|7|8|G|9|@]|A|@]|B|$]]|$2|C|4|D|6|7|8|H|9|@]|A|@]|B|$]]|$2|E|4|F|6|7|8|I|9|@]|A|@]|B|$]]]]

Assigning the file pointer to null inside your program will just get rid of that reference to the file. The file's still there. I think the <code>remove()</code> function in the c <code>stdio.h</code> is what you're looking for there. Not sure about Python.

I have text file which I want to erase in Python. How do I do that?

How to erase the file contents of text file in Python?

Python

 我有一个文本文件，我想在Python中删除它。我该怎么做呢？

问如何在Python中擦除文本文件的内容？
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