Return string using RegEx if starts with one word but not another word

Question

I would like to return the entire string if it starts with page but not pager. I tried the example below but it does not work for me.

Example of a single-pass regex that contains alpha but does not contain beta (found on this post):

^((?!beta).)*alpha((?!beta).)*$

However if you try page but not pager this does not work:

^((?!pager).)*page((?!pager).)*$

Otiel · Accepted Answer · 2011-11-15T20:57:25.460

3

This will do it:

^(?!pager)page.*$

or:

^page(?!r).*$

Both will allow 'pager' to be in the string, but not at the start.

edited Nov 15 '11 at 20:57

answered Nov 15 '11 at 20:45

Otiel

spender · Answer 2 · 2011-11-15T20:59:51.980

0

This will do:

^page(?:[^r].*)?$

edited Nov 15 '11 at 20:59

answered Nov 15 '11 at 20:49

spender

Actually, it won't work in all cases: it does not match `'page'` because with `[^r]` you ask to match any character but `'r'`. – Otiel Nov 15 '11 at 20:56
Why not use `^page([^r].*)?$` simply now? – Otiel Nov 15 '11 at 21:06
It's a habit. I use groups quite a lot, so never capture unless it's required. It doesn't matter here. – spender Nov 15 '11 at 22:17

2 Answers2