Is there a way to incorporate preg_match with total string length? I need to be able to match alphanumeric, with single underscores inside the string, with a total string length <= n.
Currently what I'm working with is this:
preg_match('/^[A-Za-z0-9]*(?:_[A-Za-z0-9]+)*$/',$string) && (strlen($string) <= 10)
I have played around with this for too long, trying to incorporate the entire thing into preg_match, so just tacked on the && strlen, but I'm sure there is a better way to do this.
Have a try with:
preg_match('/^(?=[A-Za-z0-9]*(?:_[A-Za-z0-9]+)*).{1,10}$/', $string)
edit according to comments:
/^(?=[A-Za-z0-9]+(?:_[A-Za-z0-9]+)*$).{5,25}$/
explanation:
The regular expression:
(?-imsx:^(?=[A-Za-z0-9]+(?:_[A-Za-z0-9]+)*$).{5,25}$)
matches as follows:
NODE EXPLANATION
----------------------------------------------------------------------
(?-imsx: group, but do not capture (case-sensitive)
(with ^ and $ matching normally) (with . not
matching \n) (matching whitespace and #
normally):
----------------------------------------------------------------------
^ the beginning of the string
----------------------------------------------------------------------
(?= look ahead to see if there is:
----------------------------------------------------------------------
[A-Za-z0-9]+ any character of: 'A' to 'Z', 'a' to
'z', '0' to '9' (1 or more times
(matching the most amount possible))
----------------------------------------------------------------------
(?: group, but do not capture (0 or more
times (matching the most amount
possible)):
----------------------------------------------------------------------
_ '_'
----------------------------------------------------------------------
[A-Za-z0-9]+ any character of: 'A' to 'Z', 'a' to
'z', '0' to '9' (1 or more times
(matching the most amount possible))
----------------------------------------------------------------------
)* end of grouping
----------------------------------------------------------------------
$ before an optional \n, and the end of
the string
----------------------------------------------------------------------
) end of look-ahead
----------------------------------------------------------------------
.{5,25} any character except \n (between 5 and 25
times (matching the most amount possible))
----------------------------------------------------------------------
$ before an optional \n, and the end of the
string
----------------------------------------------------------------------
) end of grouping
----------------------------------------------------------------------