Regular expression in python that check if the string just contains letters, numbers and dot(.)

Question

I am trying to develop a regular expression for match if a string just contains letters, numbers, space and dot(.) anywhere and with no order.

Like this:

hello223 3423.  ---> True
lalala.32 --->True
.hellohow1 ---> True
0you and me = ---> False (it contains =)
@newye ---> False (it contains @)
With, the name of the s0ng .---> False (it start with ,)

I am trying with this one but is always returning match:

m = re.match(r'[a-zA-Z0-9,. ]+', word)

Any idea?

Other way to formulate the question is are there any character diferent of letters, numbers, dot and space?

Thanks in advance

@AlexK. Other way to formulate the question is are there any charcater diferent of letters, numbers, dot and space? — Joan Triay, Mar 12 '18 at 14:47

score 5 · Accepted Answer · answered Mar 12 '18 at 14:48

5

You need to add $:

re.match(r'[a-zA-Z0-9,. ]+$', word)

answered Mar 12 '18 at 14:48

llllllllll

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Thanks, it seems is working, what does it mean the $? – Joan Triay Mar 12 '18 at 14:50
1

@JoanTriay It matchs the end of string. Without it, the match can be in the middle. See `$` [here](https://docs.python.org/2/library/re.html) – llllllllll Mar 12 '18 at 14:51

score 2 · Answer 2 · answered Mar 12 '18 at 14:55

2

re.search() solution:

import re

def contains(s):
    return not re.search(r'[^a-zA-Z0-9. ]', s)

print(contains('hello223 3423.'))    # True
print(contains('0you and me = '))    # False
print(contains('.hellohow1'))        # True

answered Mar 12 '18 at 14:55

RomanPerekhrest

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Considering [this `re.match` vs. `re.search`](https://stackoverflow.com/a/180993/235908) thread on StackOverflow, I'd prefer `re.search`; its match object also contains the position and content of the mismatch which might be useful for error reporting. – sshine Mar 12 '18 at 15:02

Regular expression in python that check if the string just contains letters, numbers and dot(.)

2 Answers2