Using regex and the | operator

Question

So I'm using Regex to create a change password form. Some text updates to "weak", "average", "strong" and "perfect" based on the passwords strength. I've managed to create a regex string that checks for all characters active as you can see in this string here which I would then compare with the new password string...

Regex rgxAll = new Regex(@"^(?=.*[a-z])(?=.*[A-Z])(?=.*\d)(?=.*(_|[^\w])).+$");

Though what I'm trying to do now is create a string that checks: "Does the new password contain a lowercase character AND an uppercase character OR a special character OR a number" So to simplify it into coding terms...

NewPass.IsMatch(lowercaseLetter &&(uppercaseLetter || specialChar || number);

So yeah, I'm looking to create a regex that I can use IsMatch on to check. I've tried looking online but the syntax of regex is confusing to me.

How would that look? Sorry I'm not familiar with Regex at all — Lewis, May 11 '18 at 07:02
Possible duplicate of [regex pattern lowercase and uppercase and number OR special character](https://stackoverflow.com/questions/41883854/regex-pattern-lowercase-and-uppercase-and-number-or-special-character) — Maciej Los, May 11 '18 at 07:09
I have just thought about a pattern like `^(?=[^a-z]*[a-z])(?=[a-z]*[^a-z]).*` - it will require at least 1 lowercase and at least 1 char other than lowercase ASCII letter. It is not quite the same but might be something you can consider. — Wiktor Stribiżew, May 11 '18 at 07:28
You should read [Reference - Password Validation](https://stackoverflow.com/questions/48345922/reference-password-validation) — ctwheels, May 30 '18 at 15:37

karthik manchala · Answer 1 · 2018-05-11T07:24:52.190

3

You can use the following:

^(?=.*[a-z])(?=.*[A-Z\W\d_])

Exp:

(?=.*[a-z]) : lookahead for lowercase letter
(?=.*[A-Z\W\d_]) : lookahead for uppercaseLetter || specialChar || number

edited May 11 '18 at 07:24

answered May 11 '18 at 07:04

karthik manchala

13,492
1
31
55

Note that this regex misses `_` that is considered a special char and is present in the original regex. – Wiktor Stribiżew May 11 '18 at 07:20
@WiktorStribiżew yeah.. missed that.. updated now :) – karthik manchala May 11 '18 at 07:25

3dGrabber · Accepted Answer · 2018-05-11T07:32:39.303

I'd use a single match expression per character class and then use standard boolean expressions to combine them:

var upper   = Regex.IsMatch(password, @".*[A-Z].*");
var lower   = Regex.IsMatch(password, @".*[a-z].*");
var digit   = Regex.IsMatch(password, @".*\d.*");
var special = Regex.IsMatch(password, @".*[\W_].*");

var passwordAccepted = lower && (upper || special || digit);

Which also allows you to give the user feedback why his password was rejected:

if(!digit)
{
    Console.Writeline("password must contain a number!")
}
...

Using regex and the | operator

2 Answers2