For example, if I have the following strings:
99%89 (should match)
99%? (should match)
?%99 (should match)
?%? (should not match)
?%99%99 (should match)
99%99%99%? (should match)
essentially the first or second element can be a ? or a number, but both elements cannot be ?. I tried thinking of something like:
[0-9]*|[?](?!\?)[%][0-9]*|[?]
But this does not yield the correct answer, any help would be appreciated
With your shown samples, could you please try following.
^(?:(?:\?(?:(?:%\d+){1,})?)|(?:(?:(?:\d+%){1,})?\?(?:(?:%\d+){1,})?)|(?:\d+%\d+))$
Explanation: Adding detailed explanation for above.
^(?: ##Matching from starting of the value, starting a non-capturing group from here.
(?:\? ##Starting non-capturing group(one for understanding purposes) matching literal ? here.
(?:(?:%\d+){1,})? ##In a non capturing group looking for % with 1 or more occurrences of digits and matching this group match keeping it optional.
)| ##Closing one non-capturing group here, with OR condition here.
(?: ##Starting non-capturing group(two) here.
(?:(?:\d+%){1,})?\? ##Looking for digits with % one or more occurrences in a non-capturing group keeping it optional followed by ?
(?:(?:%\d+){1,})? ##Checking for % digits one or more occurrences in a non-capturing group keeping it optional followed by ?
)| ##Closing two non-capturing group here, with OR condition here.
(?:\d+%\d+) ##In a non-capturing group looking for 1 or more digits % one or more digits
)$ ##Closing 1st non-capturing group at the end of value.
Not sure if I am reading the question right, but as you tried using a negative lookahead you could assert that the string does not only contains % and/or ?
^(?![%?]+$)[\d?%]+$
Or without a lookahead:
^[%?]*\d[%?\d]*$