Defining function to check if string is valid

Question

letters1 = "abcdefghijklmnopqrstuvwxyz"
letters2 = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"

def is_valid(strs):
    char_b = True
    for char in range(0, len(strs)):
        if strs[char] not in (letters1 or letters2):
            char_b == False
    return char_b

I don't understand why this won't work, anyone mind giving me a hint? It just always returns true.

You may use the string module (in particular string.ascii_lowercase and string.ascii_uppercase) instead of definining manually letters{}. — Bach
– Bach, Commented Feb 4, 2014 at 13:52
generally I saw people to misspell == by = but this is first example where typo is opposite!! — Grijesh Chauhan
– Grijesh Chauhan, Commented Feb 4, 2014 at 13:58

Martijn Pieters · Accepted Answer · 2014-02-04 14:28:52Z

2

You need to set char_b, not test for equality. Replace:

char_b == False

with

char_b = False

Your test is incorrect:

if strs[char] not in letters1 + letters2:

or simplify your function to:

def is_valid(strs):
    return strs.isalpha()

edited Feb 4, 2014 at 14:28

answered Feb 4, 2014 at 13:51

Martijn Pieters

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1 Comment

Brian Over a year ago

Thank you so much!! I can't believe i missed that

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