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igsm '10,440 Points
Boolean with re?
Hey. Can you help please with the following. Using RE, I want to check a string, which is meant to be a passwords. True if it contains >= 10 chars, at least one lower letter, one capital letter and one number; else False. How would a code look like. Thanks.
e.g. two cases:
True = 'bAse730onE4'
False = 'saaaa90'
Chris FreemanTreehouse Moderator 67,737 Points
Because you are looking for the
AND of multiple conditions there isn't a short single concise regexp that will solve your needs because your conditions are not order dependent. That is, you would have to check for all combinations of a condition followed by all others. For example lowercase followed by uppercase followed by number and being 10 characters long, plus the other 5 combinations,
ORed together in a single regexp.
The other option is to create the 3 search patterns and check that they each match plush a length check.
patterns =  patterns.append(re.compile(r'[a-z]+')) #lowercase patterns.append(re.compile(r'[A-Z]+')) #uppercase patterns.append(re.compile(r'[0-9]+') )# number password_good = True if len(password_string) < 10: password_good = False else: for pat in patterns: if not pat.search(password_string): # pattern not found password_good = False break
You could include the length check as a regexp:
I'll work on the combined uber-regexp to show it's complications and ammend my answer.
EDIT: Here is a single regexp pattern to match against. Yeah, it's not pretty:
In : patx = re.compile(r''' \w*[a-z]+\w*[A-Z]+\w*[0-9]+\w*| \w*[a-z]+\w*[0-9]+\w*[A-Z]+\w*| \w*[A-Z]+\w*[a-z]+\w*[0-9]+\w*| \w*[A-Z]+\w*[0-9]+\w*[a-z]+\w*| \w*[0-9]+\w*[a-z]+\w*[A-Z]+\w*| \w*[0-9]+\w*[A-Z]+\w*[a-z]+\w* ''', re.X) In : patx.search("") In : patx.search("a") In : patx.search("aA1") Out: <_sre.SRE_Match object; span=(0, 3), match='aA1'>
Now you can use:
if not len(password) > 10 and patx.search(password) print("Bad Password")
Hi Igor, re.search and re.match return match objects. If the item isn't found, it returns None (the special value). re.match checks for a match at the beginning of the string, whereas re.search checks anywhere in the string. You can use the boolean operator "and" to check multiple conditions--for example:
def check_two(string): return re.search(\w+) and re.search(\d+)
returns True if the string contains at least one word character ([a-zA-Z0-9_]) and at least one decimal digit. You can get more specific by using a set definition, like [a-z]+.