On 05Jul2016 21:37, Python List <python-list@python.org> wrote:
On 07/05/2016 03:05 PM, Seymore4Head wrote:
import os
f_in = open('win.txt', 'r')
f_out = open('win_new.txt', 'w')
for line in f_in.read().splitlines():
f_out.write(line + " *\n")
f_in.close()
f_out.close()
os.rename('win.txt', 'win_old.txt')
os.rename('win_new.txt', 'win.txt')
I just tried to reuse this program that was posted several months ago.
I am using a text flie that is about 200 lines long and have named it
win.txt. The file it creates when I run the program is win_new.txt
but it's empty.
Put a counter in your loop:
count = 0
for line in f_in.read().splitlines():
f_out.write(line + " *\n")
count += 1
print("count =", count)
Check that it says 200 (or whatever number you expect).
Not your problem, but you can simplify your read/write loop to:
for line in f_in:
f_out.write(line[:-1] + ' *\n')
The 'line[:-1]' expression gives you the line up to but not including the
trailing newline.
Alternately, use: f_out.write(line.rstrip() + ' *\n')
Importantly for this version, every line _MUST_ have a trailing newline.
Personally that is what I require of my text files anyway, but some dubious
tools (and, IMO, dubious people) make text files with no final newline.
For such a file the above code would eat the last character because we don't
check that a newline is there.
I take a hard line on such files and usually write programs that look like
this:
for line in f_in:
if not line.endswith('\n'):
raise ValueError("missing final newline on file, last line is: %r"
(line,))
f_out.write(line[:-1] + ' *\n')
Then one can proceed secure in the knowledge that the data are well formed.
I consider the final newline something of a termination record; without it I
have no faith that the file wasn't rudely truncated somehow. In other words, I
consider a text file to consist of newline-terminated lines, not
newline-separated lines.
Cheers,
Cameron Simpson <c...@zip.com.au>
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