Disapprove password if it contains exactly 4 digits (validation)
Question:
I can’t figure out how to modify my regex to make sure the password follows the last condition:
- at least 2 capital letters in a row
- doesn’t have space symbols
- contains digits
- doesn’t contain 4 consecutive digits
{4} It currently disapproves the password if it has 4 and more digits but I need it to disapprove the password with EXACTLY 4 digits.
s1 = 'annII#443'
s2 = 'annII#4343'
s3 = 'annII#43434'
pattern = r"^(?=.*[A-Z]{2,})(?=.*[A-Za-z])(?=.*[0-9])(?!.*[0-9]{4})(?!.*[s]).*$"
re.findall(pattern, s1) # ['aШnnII#443']
re.findall(pattern, s2) # []
re.findall(pattern, s3) # []
PS: It’s just a task so don’t worry. It’s not gonna be used for any real purposes.
Answers:
- To match exactly four digits, you can use at start
^ e.g. (?!(?:.*D)?d{4}(?!d)).
This requires start or a D non-digit before the 4 digits and disallows a digit after.
(?=.*[A-Za-z]) looks redundant if you already require (?=.*[A-Z]{2,}) (2 upper).{2,} two or more is redundant. {2} would suffice and does not change the logic.- Instead of
(?!.*[s]).*$ you can just use S*$ (upper matches non-whitespaces).
- It’s generally more efficient to use lazy
.*? or even a negated class where possible.
^(?=[^A-Z]*[A-Z]{2})(?=D*d)(?!(?:.*D)?d{4}(?!d))S*$
See this demo at regex101 (added n to negations in multiline demo for staying in line)
I can’t figure out how to modify my regex to make sure the password follows the last condition:
- at least 2 capital letters in a row
- doesn’t have space symbols
- contains digits
- doesn’t contain 4 consecutive digits
{4} It currently disapproves the password if it has 4 and more digits but I need it to disapprove the password with EXACTLY 4 digits.
s1 = 'annII#443'
s2 = 'annII#4343'
s3 = 'annII#43434'
pattern = r"^(?=.*[A-Z]{2,})(?=.*[A-Za-z])(?=.*[0-9])(?!.*[0-9]{4})(?!.*[s]).*$"
re.findall(pattern, s1) # ['aШnnII#443']
re.findall(pattern, s2) # []
re.findall(pattern, s3) # []
PS: It’s just a task so don’t worry. It’s not gonna be used for any real purposes.
- To match exactly four digits, you can use at start
^e.g.(?!(?:.*D)?d{4}(?!d)).
This requires start or aDnon-digit before the 4 digits and disallows a digit after. (?=.*[A-Za-z])looks redundant if you already require(?=.*[A-Z]{2,})(2 upper).{2,}two or more is redundant.{2}would suffice and does not change the logic.- Instead of
(?!.*[s]).*$you can just useS*$(upper matches non-whitespaces). - It’s generally more efficient to use lazy
.*?or even a negated class where possible.
^(?=[^A-Z]*[A-Z]{2})(?=D*d)(?!(?:.*D)?d{4}(?!d))S*$
See this demo at regex101 (added n to negations in multiline demo for staying in line)