How to match a string that doesnt contain a pattern

Question

I am trying to write a regex template that matches all the strings that doesn't contain a certain template.

E.g.:

Matches:

This is my friend. He is very nice. 

in

This is my friend. He is very nice. 

but doesn't match anything in :

  This is my friend John Michaels Fredrickson. He is very nice. 

Because it contains something like this: ([A-Z][a-z]+\s?){3}

Answer 1

You can use negative lookahead:

^(?!.*?([A-Z][a-z]+\W){3}).*$

RegEx Demo