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Regex Help c#

Posted on 2014-03-07
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Last Modified: 2014-03-20
Hi all,

I have the following regex expression in the javascript of my page;

/^(?=.*[A-Z])(?=.*[a-z])(?=.*\d)(?=.*\w){5,10}/

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I want to test a password field to be between 5 - 10 chars, contain at least 1 A-Z, at least 1 a-z, at least 1 digit and at least 1 symbol.

The password pass in javascript using the above regex but I perform a double check server side using the following method;

protected static bool CheckPassword(string password)
    {
        string sPattern = "/^(?=.*[A-Z])(?=.*[a-z])(?=.*\\d)(?=.*\\w){5,10}/";
        return System.Text.RegularExpressions.Regex.IsMatch(password, sPattern);
    }

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which is returning false where the javascript one passes?

any idea what im doing wrong here?
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Question by:flynny
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8 Comments
 
LVL 35

Expert Comment

by:Dan Craciun
ID: 39912842
I believe in C# the syntax is:
@"^(?=.*[A-Z])(?=.*[a-z])(?=.*\d)(?=.*\w){5,10}"

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or at least that's what RegexBuddy says...

HTH,
Dan
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LVL 75

Expert Comment

by:käµfm³d 👽
ID: 39912977
To add to Dan Craciun's comment, Javascript uses pattern delimiters ( / ... / ) whereas C# does not.

And actually, your pattern appears broken. You have a quantifier ( {5,10} ) that does not follow anything (except a look-ahead). Did you perhaps mean to include a dot before the quantifier?

e.g.

^(?=.*[A-Z])(?=.*[a-z])(?=.*\d)(?=.*\w).{5,10}

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LVL 35

Accepted Solution

by:
Dan Craciun earned 2000 total points
ID: 39913193
Actually, the correct syntax is:
"^(?=.*[A-Z])(?=.*[a-z])(?=.*[0-9])(?=.*[@!#$%^&]).{5,10}$"

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Without the $ it will only look at the first 10 characters, declaring any string larger than 10 chars as legit.

HTH,
Dan
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LVL 75

Expert Comment

by:käµfm³d 👽
ID: 39913214
Without the $ it will only look at the first 10 characters, declaring any string larger than 10 chars as legit.
Not quite, but I suspect that the intent was to include the end-of-line anchor.
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Author Comment

by:flynny
ID: 39917368
Hi guys thanks for this.

Just to clarify the following string;

.{5,10}$

would mean that a string between 5 - 10 chars long would be accepted?

also I notice you changed

(?=.*\w)

to be

(?=.*[@!#$%^&])

if im correct does this not mean that on of the chars in that string is required?
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LVL 35

Expert Comment

by:Dan Craciun
ID: 39917384
.{5,10} means repeat the previous group (which is . or any character) 5 to 10 times.

$ means end of line

\w means any word character (letter, digit or underscore) - it won't match special characters

[] means any of the characters enclosed.

(?=.*[@!#$%^&]) means that your string needs to have at least one of the characters between brackets.

HTH,
Dan
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Author Closing Comment

by:flynny
ID: 39941793
perfect,
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LVL 35

Expert Comment

by:Dan Craciun
ID: 39941801
Glad I could help!
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