java regex until certain word/text/characters

Question

Please consider the following text :

That is, it matches at any position that has a non-word character to the left of it, and a word character to the right of it.

How can I get the following result :

That is, it matches at any position that has a non-word character to the 

That is everything until left

Answer 1

input.replace("^(.*?)\\bleft.*$", "$1");

• ^ anchors to the beginning of the string
• .*? matches as little as possible of any character
• \b matches a word boundary
• left matches the string literal "left"
• .* matches the remainder of the string
• $ anchors to the end of the string
• $1 replaces the matched string with group 1 in ()

If you want to use any word (not just "left"), be careful to escape it. You can use Pattern.quote(word) to escape the string.

Answer 2

The answer is actually /(.*)\Wleft\w/ but it won't match anything in

That is, it matches at any position that has a non-word character to the left of it, and a word character to the right of it.