I need a regex that tests a string for a
- minimum of 14 characters – valid are
A-Za-z0-9#,.-_
- minimum of 6 letters within that 14
- minimum of 2 numbers within that 14
Is there a way I can wrap this up in one regular expression (currently I have a javascript and php function that does three separate tests, one that it is 14 total, another that there is at least two numbers, and another that there is at least 6 letters.
So the following would be valid:
- blabla2bla2f54a (valid >14 total, with at least 6 letters, at least 2 numbers)
- thisIsNotValidAtAll (invalid because less than 2 numbers)
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Answer
Easy! First lets look at a commented version in PHP:
$re = '/# Match 14+ char password with min 2 digits and 6 letters. ^ # Anchor to start of string. (?=(?:.*?[A-Za-z]){6}) # minimum of 6 letters. (?=(?:.*?[0-9]){2}) # minimum of 2 numbers. [A-Za-z0-9#,.-_]{14,} # Match minimum of 14 characters. $ # Anchor to end of string. /x';
Here is the JavaScript version:
var re = /^(?=(?:.*?[A-Za-z]){6})(?=(?:.*?[0-9]){2})[A-Za-z0-9#,.-_]{14,}$/;
Addendum 2012-11-30
I noticed that this answer recently got an upvote. This uses a more outdated expression so I figured it was time to update it with a better one.
=== A more efficient expression ===
By getting rid of the “dot-star” altogether and greedily applying a more precise expression, (a negated char class), an even more efficient solution results:
$re = '/# Match 14+ char password with min 2 digits and 6 letters. ^ # Anchor to start of string. (?=(?:[^A-Za-z]*[A-Za-z]){6}) # minimum of 6 letters. (?=(?:[^0-9]*[0-9]){2}) # minimum of 2 numbers. [A-Za-z0-9#,.-_]{14,} # Match minimum of 14 characters. $ # Anchor to end of string. /x';
Here is the new JavaScript version:
var re = /^(?=(?:[^A-Za-z]*[A-Za-z]){6})(?=(?:[^0-9]*[0-9]){2})[A-Za-z0-9#,.-_]{14,}$/;
- Edit 1: Added
#,.-_
to list of valid chars. - Edit 2: Changed the greedy to lazy star.
- Edit 2012-11-30: Added alternate version with the “lazy-dot-star” replaced with a more efficient greedy application of a more precise expression.