[regex] Why unexpected hit?

[Shohreh]

Hello,

I need to find only lines that begin with three capital letters, so I used the following:

^[A-Z]{3}

For some reason, NP++ also finds the line that starts with “Bur”. Why is that?

I know I can check the “Match Case” option but I shouldn’t have to.

Thank you.

[PeterJones]

@Shohreh said in [regex] Why unexpected hit?:

I know I can check the “Match Case” option but I shouldn’t have to.

Yes you should. That checkmark literally tells the regular expression engine whether to do case sensitive or case-insensitive matching. With “match case” off, then U in the regex matches U or u in the text, whether it’s in the regular expression as a literal U or whether it’s in a range like [A-Z].

If you don’t like clicking a checkbox, you could instead use the regular expression command that forces case sensitivity, specifically (?-i) (“turn off case-insensitive matching”), so your regex could be (?-i)^[A-Z]{3} to force case-sensitive matching.

But you absolutely, positively must set case sensitivity on via one of those two methods if you want any U in the regex to only match uppercase U and not lowercase u – that’s literally what “case sensitive”/“match case” vs “case insensitive”/“don’t match case” means.

[Shohreh]

@PeterJones Thank you.