Regex to match but not include a word before another word

Question

I have two specific words in a line say dog and cat.

And say dog appears before cat.

How do I make a regex which tells me all the lines containing dog and cat, but show just the words after dog till cat, including cat, but NOT dog.

Answer 1

Option 1: Lookbehind

(?<=dog).*?cat

Details:

• The (?<=dog) lookbehind asserts that what precedes the current position is dog
• .*? lazily matches all characters up to...
• cat matches literal characters

Option 2: \K (PCRE, Perl, Ruby 2+)

dog\K.*?cat

The \K tells the engine to drop what was matched so far from the final

Option 3: Capture Group (JavaScript and other engines that don't support the other two options)

dog(.*?cat)

The parentheses capture what you want to Group 1. You have to retrieve the match from Group 1 in your language.