in reply to Difficult? regex

/\?(C=N;O=D|C=M;O=A)?$/; ^

WHy do you need that last question mark? That way it will also match \?$. Probably not what you want.

It would also help if your error description was better than "DOESN'T WORK AS EXPECTED"

Replies are listed 'Best First'.
A reply falls below the community's threshold of quality. You may see it by logging in.