[checkio] House password

[checkio] House password

((?=.*\d)(?=.*[a-z])(?=.*[A-Z])(?=.*[@#$%]).{6,20})

위의 코드를 참고하여 작성합니다.

import re

def checkio(data):
    rst = re.match('((?=.*\d)(?=.*[a-z])(?=.*[A-Z]).{10,})', data)
    return bool(rst)

re.match(…) 코드에서 매치가 되지 않으면 none이 반환되므로 bool() 함수를 사용하여 반환합니다.

Regular Expression

?= positive lookahead 를 사용하여 찾습니다.

(?=.*\d) : 숫자가 포함된 것을 확인한다.
(?=.*[a-z]) : 소문자가 포함된 것을 확인한다.
(?=.*[A-Z]) : 대문자가 포함된 것을 확인한다.
.{10,} : 길이가 10이상인 것을 확인한다.

(?!) - negative lookahead
(?=) - positive lookahead
(?<=) - positive lookbehind
(?<!) - negative lookbehind
(?>) - atomic group

positive lookahead (?=ABC)

Matches a group after the main expression without including it in the result.

example

\d(?=px)
1pt 2px 3em 4px

negative lookahead (?!ABC)

Specifies a group that can not match after the main expression (if it matches, the result is discarded).

example

\d(?!px)
1pt 2px 3em 4px

positive lookbehind (?<=ABC)

Matches a group before the main expression without including it in the result

negative lookbehind (?<!ABC)

Specifies a group that can not match before the main expression (if it matches, the result is discarded)

ref

• http://www.mkyong.com/regular-expressions/how-to-validate-password-with-regular-expression/
• https://docs.python.org/2/library/re.html
• https://wikidocs.net/1642
• https://checkio.org/mission/house-password
• http://stackoverflow.com/questions/2973436/regex-lookahead-lookbehind-and-atomic-groups
• http://www.regular-expressions.info/lookaround.html
• http://regexr.com/