Question

I have a need to search all numbers with 4 digits between 2000 and 3000.

It can be that letters are before and after.

I thought I can use [2000-3000]{4}, but doesnt work, why?

thank you.

Answer 1

How about

^2\d{3}|3000$

Or as Amarghosh & Bart K. & jleedev pointed out, to match multiple instances

\b(?:2[0-9]{3}|3000)\b

If you need to match a3000 or 3000a but not 13000, you would need lookahead and lookbefore like

(?<![0-9])(?:2[0-9]{3}|3000)(?![0-9])