Add minimum characters to 'bad word' regex? - php

Question

I made a regex that captures 'bad words' and substitutes with *** so I can return to user in a form if bad words found, a simplified version can be found here:
https://regex101.com/r/alEb61/3
(?i)\b(Bitch)\b
I'd like to also require min 25 characters in the same regex instead of having to run two separate passes on it (e.g. 1) Bad Words 2) Enough Chars?) is that possible? I basically need to add to above some "less than 25 characters" pipe.

Answer 1

Regex minimum is {min,max} so {1,15} Min of 1 character, max of 15.
I'd do a list of "bad words" then say at least 1 must exist
As far as regex limit goes /^[word]{1,15}$/ - Must be 1 -> 15 "word" found
Check this post out Profanity Filter using a Regular Expression (list of 100 words)

Answer 2

If you plan to replace any bad word on your list and the whole string shorter than 25 chars, use
$s = preg_replace('~^.{0,24}$|\b(?:badWord1|badWordN)\b~i', 'CENSURED', $s);
See the regex demo.
Details
^.{0,24}$ - first alternative
| - or
\b(?:badWord1|badWordN)\b- the second alternative:
\b - leading word boundary
(?: - start of an alternation non-capturing group
badWord1 - bad word #1
| - or
badWordN - bad word N
) - end of the group
\b - a trailing word boundary.
If you plan to match any string longer than 24 chars and not having bad words in it, use
'/^(?!.*\bbadword\b).{25,}$/s'
It will match a string that has at least 25 chars and does not contain badword as a whole word.
See a regex demo.
Details
^ - start of string
(?!.*\bbadword\b) - a negative lookahead that fails the match if after any 0+ chars there is a whole word badword
.{25,} - any 25 or more chars'
$ - end of string.

Answer 3

In the end I created my own version as what I wanted to do was only capture matches IF there was a "bad word" or if there were less than X.
^(?i)(?P<Words>\bBadWord1|BadWordN\b)|(?P<Characters>^.{0,25}$)$
which can be tested here
This served my purpose as
if there are no bad words and > 25 chars it returns no matches and the substitution is not even needed (but can be used)
If there are bad words it indicates that and also substitutes them with * so I can replace the user input text with an alert to replace 'Bad Words' and I know this is the error since the Capture Group is named Words
If there are no bad words but not enough characters it will return the Capture Group as Characters so I can return that alert instead.