Python: If Statement For Reading Txt Files

Question

Here is my code:

print "Note: Your file is available now."
viewYourFile = raw_input("\nDo you wish to view this file now? ")

if viewYourFile == 'Y' or 'y':
    fo = open('messages.txt', 'r+')
    #Read whole file into data
    data = fo.read()
    print data
    # Close the file
    fo.close()
elif viewYourFile == 'N' or 'n': 
    print "Thank you!"
else:
    print "Didn't recognize user input"

When I type in 'n' the text file still opens. If the user types in 'N' or 'n' I want the script to move on without printing the text into the terminal.

I can't spot anything obvious that I've done wrong. Can someone take a second look for me? Many thanks.

@BubbleMonster if you get answer select one. – Nilesh Sep 05 '13 at 12:03 — Nilesh, Sep 05 '13 at 12:03

score 3 · Accepted Answer · edited May 23 '17 at 10:25

3

if viewYourFile == 'Y' or 'y': always evaluates to True since the second condition 'y' is always True.

>>> bool('y')
True
>>> bool(False or 'y')
True

Use if viewYourFile in ('Y', 'y'): instead.

Also, instead of closing the file manually, use with context manager. Here's the resulting code:

print "Note: Your file is available now."
viewYourFile = raw_input("\nDo you wish to view this file now? ")

if viewYourFile in ('Y', 'y'):
    with open('messages.txt', 'r+') as fo:
        data = fo.read()
elif viewYourFile in ('N', 'n'): 
    print "Thank you!"
else:
    print "Didn't recognize user input"

Also see:

How do I test one variable against multiple values?

edited May 23 '17 at 10:25

Community

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1

answered Sep 05 '13 at 11:49

alecxe

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Thanks that works. Can you explain why that evaluates to true but it doesn't using brackets? – BubbleMonster Sep 05 '13 at 11:52
@BubbleMonster you are welcome, see updated answer, hope it's clear. – alecxe Sep 05 '13 at 11:55
@BubbleMonster also see explanations here: http://stackoverflow.com/questions/15112125/if-x-or-y-or-z-blah – alecxe Sep 05 '13 at 11:56
Thanks yes that makes sense, however, when I do: with open('messages.txt', 'r+') as fo - I get an error: Invalid syntax. Not too sure why. – BubbleMonster Sep 05 '13 at 11:59
@BubbleMonster oh, sorry, missed colon, edited, give it a try. – alecxe Sep 05 '13 at 11:59
Perfect. Thanks. Much better way of doing it. – BubbleMonster Sep 05 '13 at 12:01

score 2 · Answer 2 · edited May 23 '17 at 12:05

2

You should do:

if viewYourFile == 'Y' or viewYourFile == 'y':

or as like @alecxe suggested, i.e.:

if viewYourFile in ('Y', 'y'):

Another good way that includes less typing is:

if viewYourFile.lower() == 'y':

edited May 23 '17 at 12:05

Community

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answered Sep 05 '13 at 11:52

Santosh Kumar

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Thanks Santosh. Voted up for that info. Wasn't aware that I would have to declare the variable twice using one parameter! – BubbleMonster Sep 05 '13 at 11:55

score 1 · Answer 3 · answered Sep 05 '13 at 11:51

1

More smarter I think lead to one register:

if viewYourFile.lower() == 'y':

answered Sep 05 '13 at 11:51

Denis

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Python: If Statement For Reading Txt Files

3 Answers3