blocks|key|1614706|text|你不能写到文件的中间。最简单的解决方案是将文件读入内存，替换文本，然后将其写回。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1614707|with+open('file_name')+as+f:
++++text+=+f.read()

text+=+text.replace('hellohello',+'hello')

with+open('file_name',+'w')+as+f:
++++f.write(text)|code-block|syntax|javascript|1614708|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

You can't write to the middle of a file. The easiest solution would be to read the file into memory, replace the text and then write it back out.

<pre><code>with open('file_name') as f:
 text = f.read()

text = text.replace('hellohello', 'hello')

with open('file_name', 'w') as f:
 f.write(text)
</code></pre>

blocks|key|733638|text|完成这类简单任务的最简单方法是从文件中读取所有数据，执行替换，然后将新数据写入文件。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|733639|下面是一些示例代码，说明您似乎正在尝试执行的操作：|733640|filename+=+"/tmp/a.txt"
with+open(filename,+'r')+as+f:
++data+=+f.read()
with+open(filename,+'w')+as+f:
++f.write(data.replace("hellohello",+"hello"))|code-block|syntax|javascript|733641|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|L|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|M|8|@]|9|@]|A|$G|H]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

The easiest way to go for a simple task such as this is to read all the data from the file, perform the substitution, and then write the new data to the file.

Here is some sample code for what you appear to be trying to do:

<pre><code>filename = "/tmp/a.txt"
with open(filename, 'r') as f:
 data = f.read()
with open(filename, 'w') as f:
 f.write(data.replace("hellohello", "hello"))
</code></pre>

blocks|key|733674|text|另一种方法是读取整个文件，然后写回您的文本，可以使用临时文件。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|733675|您可以在读取时逐行写入临时文件，最后将原始文件替换为临时文件：|733676|import+shutil

filename+=+'a.txt'
temp+=+'copy.tmp'
with+open(filename,+'r')+as+input_file,+open(temp,+'w')+as+output_file:
++++for+line+in+input_file:
++++++++output_file.write(line.replace('hellohello','hello'))

shutil.move(temp,+filename)|code-block|syntax|javascript|733677|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|L|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|M|8|@]|9|@]|A|$G|H]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

An alternative to read the whole file and then write back your text, can be to use a temp file.

You can write line by line to a temporary file while you read and at the end replace your orignal file with the temp one:

<pre><code>import shutil

filename = 'a.txt'
temp = 'copy.tmp'
with open(filename, 'r') as input_file, open(temp, 'w') as output_file:
 for line in input_file:
 output_file.write(line.replace('hellohello','hello'))

shutil.move(temp, filename)
</code></pre>

blocks|key|4770966|text|你真的应该努力改进你的代码。首先，在处理文件时，我建议尽可能使用os模块，而不是使用字符串连接。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4770967|所以你可以使用os.path.join('/tmp',+files)而不是file_name="/tmp/"%2Bstr(files)。您还可以使用name,+extension+=+os.path.splitext(ff)获取文件扩展名，并且可以测试扩展名是否符合您的需要。|offset|length|style|CODE|4770968|另外，从算法的角度来看，我不明白为什么要迭代目录中的所有文件，将它们放在一个列表中，然后再次迭代该列表来进行处理。你也可以这样做：|4770969|+++for+ff+in+os.listdir('/tmp'):
+++++++if+os.path.splitext(ff)[1]+==+".txt":
+++++++++++file_n+=+os.path.join('/tmp',+ff)
+++++++++++with+open(file_n,+'r')+as+file_p:
+++++++++++++++text+=+file_p.read().replace('hellohello+world',+'hello+world')
+++++++++++with+open(file_n,+'w')+as+file_p:
+++++++++++++++file_p.write(text)|code-block|syntax|javascript|4770970|这应该就是你所需要的了。|4770971|entityMap^0|0|7|R|11|S|20|12|0|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|T|8|@$D|U|E|V|F|G]|$D|W|E|X|F|G]|$D|Y|E|Z|F|G]]|9|@]|A|$]]|$1|H|3|I|5|6|7|10|8|@]|9|@]|A|$]]|$1|J|3|K|5|L|7|11|8|@]|9|@]|A|$M|N]]|$1|O|3|P|5|6|7|12|8|@]|9|@]|A|$]]|$1|Q|3|-4|5|6|7|13|8|@]|9|@]|A|$]]]|R|$]]

You should really work on improving you code imo. First when working with files I recommend using the os module whereever possible instead of using string concatenation.

So instead of: <code>file_name="/tmp/"+str(files)</code> you could do <code>os.path.join('/tmp', files)</code>. You can also get the file extension with <code>name, extension = os.path.splitext(ff)</code> and the you can test if the extension is what you need.

Also from an algorithmical point of view I don't see why you iterate over all the files in the directory, put them in a list, then iterate over that list again to do the processing. You could just as well do:

<pre><code> for ff in os.listdir('/tmp'):
 if os.path.splitext(ff)[1] == ".txt":
 file_n = os.path.join('/tmp', ff)
 with open(file_n, 'r') as file_p:
 text = file_p.read().replace('hellohello world', 'hello world')
 with open(file_n, 'w') as file_p:
 file_p.write(text)
</code></pre>

And that should be pretty much all you need.

blocks|key|733756|text|你可以使用fileinput模块就地替换文件中的字符串(不需要在你的代码中打开两个文件或打开同一个文件两次或将整个文本文件加载到内存中)。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|733757|#!/usr/bin/python
import+os
import+fileinput

new_file_list=[]
all_files=os.listdir("/tmp")
for+ff+in+all_files:
+if+ff.endswith(".txt"):
++++new_file_list.append(ff)

for+files+in+new_file_list:
+print+files
+if+files+==+"a.txt":
+++print+"======================================="
+++file_name="/tmp/"%2Bstr(files)
+++print+file_name

+++f+=+fileinput.FileInput(file_name,+inplace=1)

+++print+"======================================="
+++for+line+in+f:
++++++++line+=+line.replace("hellohello","hello")
++++++++print+line,
+++f.close()|code-block|syntax|javascript|733758|entityMap|0|LINK|mutability|MUTABLE|url|http://docs.python.org/library/fileinput.html^0|5|9|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@$A|R|B|S|1|T]]|C|$]]|$1|D|3|E|5|F|7|U|8|@]|9|@]|C|$G|H]]|$1|I|3|-4|5|6|7|V|8|@]|9|@]|C|$]]]|J|$K|$5|L|M|N|C|$O|P]]]]

You can use <a href="http://docs.python.org/library/fileinput.html" rel="nofollow">fileinput</a> module to replace string in a file in place (without opening two files or opening the same file twice or loading entire text file into memory in your code).

<pre><code>#!/usr/bin/python
import os
import fileinput

new_file_list=[]
all_files=os.listdir("/tmp")
for ff in all_files:
 if ff.endswith(".txt"):
 new_file_list.append(ff)

for files in new_file_list:
 print files
 if files == "a.txt":
 print "======================================="
 file_name="/tmp/"+str(files)
 print file_name

 f = fileinput.FileInput(file_name, inplace=1)

 print "======================================="
 for line in f:
 line = line.replace("hellohello","hello")
 print line,
 f.close()
</code></pre>

In the below code i am trying to replace the contents of a file which has the following content in it.
<code>hellohello world</code> and the string hellohello should be replaced by hello and be wrote back to the file.Ho to go about this

<pre><code> #!/usr/bin/python
 import os

 new_file_list=[]
 all_files=os.listdir("/tmp")
 for ff in all_files:
 if ff.endswith(".txt"):
 new_file_list.append(ff)

 for files in new_file_list:
 if files == "a.txt":
 print "======================================="
 file_name="/tmp/"+str(files)
 print file_name
 f=open(file_name ,"rw")
 while True:
 print "======================================="
 for line in f.readline():
 print line
 print "======================================="
 f.write(line.replace("hellohello","hello"))
 print line
 else:
 break
 for line in f.readline():
 print line

 f.close()
</code></pre>

python search and write to file

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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在下面的代码中，我试图替换一个包含以下内容的文件的内容。应该将hellohello world和字符串hellohello替换为hello，并将其写回file.Ho以执行此操作  #!/usr/bin/python  import os  new_file_list=[]  all_files=os.listdir("...

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