fork download 
  1. import re
  2. text = "1. 1xyz-2xyz - it's OK\n2. 1-2xyz - it's OK\n3. 1xyz - it's OK\n4. 1-2 - there should be no match"
  3. pattern = r"\b([0-9])(xyz)?(?:-([0-9])(xyz)?)?\b(?(2)|(?(4)|(?!)))"
  4. print( [x.group() for x in re.finditer(pattern, text)] )
Success #stdin #stdout 0.03s 9680KB
comments (?)
stdin 
Standard input is empty
stdout 
['1xyz-2xyz', '1-2xyz', '1xyz']
https://ideone.com/bum3lE
language:
Python 3 (python  3.12)
created:
2 years ago
visibility:
secret

Share or Embed source code

Discover > Sphere Engine API

The brand new service which powers Ideone!

Discover > IDE Widget

Widget for compiling and running the source code in a web browser!