Complex regular expression

Question

I want to capture a substring of a string choosing the number of characters, but if any word is cut then get until the last blank.

As example if this is the text:

"This is an example of text lorem ipsum, etc..."

12 characters would give "This is an e". In this case the last word is cut, so the result should be "This is an".

Its possible do this with Regular Expressions?

Answer 1

^.{0,11}\w\b

This will find 12 characters where the last one is a word character \w followed by a word break \b. A word break is a zero-length assertion which matches either the beginning or end of a word.

Result: The \w\b ensures that the final character of the match is the last character of a word so you don't get a partial word.