asked on

Regex for alphanumeric only

* must contain both upper and lowercase characters
* must contain at least one number
* must only contain letters and numbers (no other special characters)
* min length 7, max length 12

The following is close:
^(?=.*\d)(?=.*[a-z])(?=.*[A-Z])(?!.*[@#$%^&+=]).{7,12}$

but there is a danger i could miss characters in the exclude list. Is there anyway to specify just alphanumeric only?

Thanks

Todd Gerbert

^(?=.*\d)(?=.*[a-z])(?=.*[A-Z])([0-9a-zA-Z]){7,12}$

ASKER CERTIFIED SOLUTION

Todd Gerbert

membership

This solution is only available to members.

To access this solution, you must be a member of Experts Exchange.

Start Free Trial

Sandy209

ASKER

Excellent! Thanks

Mike_Mozhaev

I would not use regex in this case. Finite state machine would be much simpler.

Something like:

bool upperCaseFound = false;
bool lowerCaseFound = false;
bool digitFound = false;

foreach (char c in s)
{
switch (char.GetUnicodeCategory(c))
{
case UnicodeCategory.UppercaseLetter:
upperCaseFound = true;
break;

case UnicodeCategory.LowercaseLetter:
lowerCaseFound = true;
break;

case UnicodeCategory.DecimalDigitNumber:
digitFound = true;
break;
}
}

bool validPassword =
lowerCaseFound &&
upperCaseFound &&
digitFound &&
s.Length >= 7 &&
s.Length <= 12;