Regex for alphanumeric password, with at least 1 number and character

Question

Need help with a regex for alphanumeric password, with at least 1 number and character, and the length must be between 8-20 characters.

I have this but doesn\'t seem

Answer 1

Wouldn't it be better to do this validation with some simple string functions instead of trying to shoehorn a difficult to validate regex into doing this?

Answer 2

This code is for javascript

// *********** ALPHA-Numeric check ***************************
function checkAlphaNumeric(val)
{
    var mystring=new String(val)

    if(mystring.search(/[0-9]+/)==-1) // Check at-leat one number
    {
        return false;
    }
    if(mystring.search(/[A-Z]+/)==-1 && mystring.search(/[a-z]+/)==-1) // Check at-leat one character
    {
        return false;
    }
}

Answer 3

Something like this will be closer to your needs. (I didn't test it, though.)

Regex test = new Regex("^(?:(?<ch>[A-Za-z])|(?<num>[9-0])){8,20}$");
Match m = test.Match(input);
if (m.Success && m.Groups["ch"].Captures.Count > 1 && m.Groups["num"].Captures.Count > 1)
{
  // It's a good password.
}

Answer 4

^(?=.{8,20}$)(?=.*[0-9])(?=.*[a-zA-Z]).*

? :)

Answer 5

Why not just use a handful of simple functions to check?

checkPasswordLength( String password);
checkPasswordNumber( String password);

Maybe a few more to check for occurrences of the same character repeatedly and consecutively.

Answer 6

If you take a look at this MSDN link, it gives an example of a password validation RegEx expression, and (more specifically) how to use it in ASP.NET.

For what you're looking to accomplish, this should work:

    (?!^[0-9]*$)(?!^[a-zA-Z]*$)^([a-zA-Z0-9]{8,20})$

This requires at least one digit, at least one alphabetic character, no special characters, and from 8-20 characters in length.