擅长:python、mysql、java
<p>你可以这样做:</p>
<pre><code> lines=[]
with open('path_to_file', 'r+') as source:
for line in source:
line = line.replace('\n','').strip()
if line.split()[-1] != 'sent':
# do some operation on line without 'sent' tag
do_operation(line)
# tag the line
line += '\tsent'
line += '\n'
# temporary save lines in a list
lines.append(line)
# move position to start of the file
source.seek(0)
# write back lines to the file
source.writelines(lines)
</code></pre>