Simple I/O problem can't get solved
Greetings to everybody,
I have recently started to solve my first Python problems but I came across to
this:
Write a version of a palindrome recogniser that accepts a file name from the
user, reads each line, and prints the line to the screen if it is a
palindrome.(by http://www.ling.gu.se/~lager/python_exercises.html)
I think I coded it correctly but still I get no output. I do not have any
errors I just do not get any output.
This is the code:
***
import is_palindrome
filename = raw_input('Enter a file: ') # A text file
f = open(filename)
while True:
line = f.readline()
if len(line) == 0:
break
elif is_palindrome.is_palindrome(line):
print line,
f.close()
***
I have coded the is_palindrome module before and it works very well.
Here is this module's code:
***
def reverse(text):
return text[::-1]
def replace_all(text, dic):
for i, j in dic.iteritems():
text = text.replace(i, j)
return text
def is_palindrome(text):
return text == reverse(text)
points = {'.':'', ',':'', '!':'', ';':'', '?':'', '/':'', '\\':''}
something = raw_input('Enter text: ').lower().replace(' ', '')
replace = replace_all(something, points)
if is_palindrome(replace):
print 'Yes, it is a palindrome:', reverse(replace)
else:
print 'No, it is not a palindrome:', reverse(replace)
***
What should I do to output only the palindrome lines from the text file?
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Re: Simple I/O problem can't get solved
Τη Παρασκευή, 21 Ιουνίου 2013 12:15:59 μ.μ. UTC+3, ο χρήστης Peter Otten έγραψε:
> nickgan@windowslive.com wrote:
>
>
>
> > I have recently started to solve my first Python problems but I came
>
> > across to this:
>
> > Write a version of a palindrome recogniser that accepts a file name from
>
> > the user, reads each line, and prints the line to the screen if it is a
>
> > palindrome.(by http://www.ling.gu.se/~lager/python_exercises.html)
>
> >
>
> > I think I coded it correctly but still I get no output. I do not have any
>
> > errors I just do not get any output.
>
> >
>
> > This is the code:
>
>
>
> > import is_palindrome
>
> >
>
> > filename = raw_input('Enter a file: ') # A text file
>
> > f = open(filename)
>
> > while True:
>
> > line = f.readline()
>
>
>
> The line includes the trailing newline character which breaks the symmetry:
>
>
>
> >>> "abba" == "abba"[::-1]
>
> True
>
> >>> "abba\n" == "abba\n"[::-1]
>
> False
>
>
>
> Use
>
>
>
> word = line.strip()
>
>
>
> to remove all leading and trailing whitespace.
>
>
>
> > if len(line) == 0:
>
> > break
>
> > elif is_palindrome.is_palindrome(line):
>
> > print line,
>
> > f.close()
>
>
>
> Note that python allows you to iterate over the lines of a file with
>
>
>
> for line in f:
>
> ...
>
>
>
> Combining these modifications:
>
>
>
> for line in f:
>
> word = line.strip()
>
> if is_palindrome.is_palindrome(word):
>
> print word
Thank you a lot it worked!
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