Python中的if / else循环问题

Question

I am trying to make this Pig Latin translator in Python and it was working well until I tried to downsize it a bit.

Can someone please take a look at this code and tell me why, when I type in a word without a vowel at the beginning it will still print the "vowel" code in this if statement?

CODE:

pyg = 'ay'

original = raw_input('Enter a word: ')
low_original = original.lower()

if len(low_original) > 0 and low_original.isalpha():
        print low_original
        if low_original[0] == 'a' or 'e' or 'i' or 'o' or 'u':
                print "vowel"
                pyg_vowel = low_original + pyg
                print pyg_vowel
        else:
                print "consonant"
                pyg_cons = low_original[1: ] + low_original[0] + pyg
                print pyg_cons
else:
        print 'empty'

Answer 1

You need to do a check for all the vowels separately.

Currently, your if condition is evaluated as: -

if (low_original[0] == 'a') or 'e' or 'i' or 'o' or 'u':

or returns the first true value in its condition, which will either True or e here, depending upon your first condition is True or not. Now, since 'e' is evaluated to True , so both the values are true , hence your condition will always be true .

You should do it like this: -

if low_original[0] in 'aeiou':

or: -

if low_original[0] in ('a', 'e', 'i', 'o', 'u'):

Answer 2

You should replace the string:

if low_original[0] == 'a' or 'e' or 'i' or 'o' or 'u':

with:

if low_original[0] in ('a', 'e', 'i', 'o', 'u'):

Answer 3

The if is alwasys returning True!

pyg = 'ay'

original = raw_input('Enter a word: ')
low_original = original.lower()

if len(low_original) > 0 and low_original.isalpha():
    print low_original
    if low_original[0] in ['a' , 'e' , 'i' , 'o' , 'u']:
            print "vowel"
            pyg_vowel = low_original + pyg
            print pyg_vowel
    else:
            print "consonant"
            pyg_cons = low_original[1: ] + low_original[0] + pyg
            print pyg_cons
else:
    print 'empty'

Answer 4

The problem is in 'if low_original[0] == 'a' or 'e' or 'i' or 'o' or 'u':' - first is not pythonic second is not giving you not what you expect.

Try to update your code to:

pyg = 'ay'

original = raw_input('Enter a word: ')
low_original = original.lower()

if len(low_original) > 0 and low_original.isalpha():
    print low_original
    if low_original[0] in ('a', 'e', 'i', 'o', 'u'):
            print "vowel"
            pyg_vowel = low_original + pyg
            print pyg_vowel
    else:
            print "consonant"
            pyg_cons = low_original[1: ] + low_original[0] + pyg
            print pyg_cons
else:
    print 'empty'

Answer 5

将if语句替换为

if low_original[0] in ['a', 'e', 'i', 'o', 'u']

Answer 6

The condition in this if will always evaluate to True .

 if low_original[0] == 'a' or 'e' or 'i' or 'o' or 'u':
            print "vowel"
            pyg_vowel = low_original + pyg
            print pyg_vowel

It's the same as if (low_original[0] == 'a') or 'e' or 'i' or 'o' or 'u'

You should use something like if low_original[0] in 'aeiou'