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:

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

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Todd GerbertIT ConsultantCommented:
Todd GerbertIT ConsultantCommented:
I think this is better.


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Sandy209Author Commented:
Excellent!  Thanks
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;

        case UnicodeCategory.LowercaseLetter:
            lowerCaseFound = true;

        case UnicodeCategory.DecimalDigitNumber:
            digitFound = true;

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

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