Difference in regex between Perl and Python?

Question

I have several email addresses, '[e-mail]'and '[e-mail]'.

In perl, I could take a string of To:raw mail and find any of the above addresses with

/\w+@(tickets\.)?company\.com/i

In python, I just wrote the above expression as '\w+@(tickets\.)?company\.com'expecting the same result. However, [e-mail] was not found at all, and findall on the second returns a list containing only 'tickets.'. It’s so clear that '(tickets\.)?'this is a problem area, but what is the difference between the regex rules between Perl and Python that I miss?

Answer 1

re.findall:

findall(pattern, string, flags=0)
    Return a list of all non-overlapping matches in the string.

    If one or more groups are present in the pattern, return a
    list of groups; this will be a list of tuples if the pattern
    has more than one group.

    Empty matches are included in the result.

(tickets\.) - , findall . , / , ..

r'(\w+@(tickets\.)?company\.com)'
r'\w+@(?:tickets\.)?company\.com'

, , findall .

Answer 2

, . Python:

'(\w+@(?:tickets\.)?company\.com)'

Answer 3

:

• , "\"
• "."

, :

r'\w+@(tickets\.)?company\.com'

:

>>> import re
>>> exp = re.compile(r'\w+@(tickets\.)?company\.com')
>>> bool(exp.match("[e-mail]"))
True
>>> bool(exp.match("[e-mail]"))
True

Answer 4

There is no difference in regular expressions, but there is a difference in what you are looking for. Your regular expression captures only "tickets."if it exists in both regular expressions. You probably want something like this

#!/usr/bin/python

import re

regex = re.compile("(\w+@(?:tickets\.)?company\.com)");

a = [
    "[e-mail]", 
    "[e-mail]", 
    "[e-mail]",
    "[e-mail]"
];

for string in a:
    print regex.findall(string)