Question

I am a novice in regex and trying to understand it by solving small problems. So here I am with a problem which I couldn’t solve (warning: it may be extremely silly). Your inputs will help me understand the concept.

I want to write a regex which will match all items in list1 but none of those from list2

list1

   pit
   spot
   spate
   slap two
   respite

list2

   pt
   Pot
   peat
   part

I was thinking like “give me all the items that starts with p|s|r and endswith it|ot|e|o
So i wrote ^[p|s|r].*[it|ot|e|o]$ which eventually resulted in undesired result.

Thanks in advance for your inputs.

Answer 1

In notepad you can’t do or operations (taken from Notepad++: A guide to using regular expressions and extended search mode and tested on my Notepad++ 5.9.3)

This would work in other “standard” regexes 🙂

^[psr].*(it|ot|e|o)$

Try here. http://gskinner.com/RegExr/?2uudn

What were you doing was using the [] instead of the grouping (). It was equivalent to: [itoe|] (were the | was a “standard” character instead of or) and in general everything in an [] is in or 🙂 [ab] means a or b.