How to find lines not containing (matching) a string in Notepad++

 In Notepad++, you might have a requirement to find or replace lines which do NOT match a particular string.
Lets say you have the following lines in your text file - and you would like to the find lines NOT containing the string "USA"

Apple - USA
Airbus - France
Google -USA
IBM - USA
SAP - Germany
TESCO - UK

For this, you will have to use the Notepad++ Regex find option

Here's how:

• Press Ctrl + F to pop open the Find dialog box
• Select the Regular Expression radio button
• Type in the find box : ^(?!.*USA).*$ 
• Now find or replace.

Here are couple of awesome books to understand more about Regular expressions :

• Mastering Regular Expressions - by Jeffrey Friedl ( Amazon.com | Amazon.in ) 
• Regular Expressions Cookbook by Jan Goyvaerts, Steve Levithan ( Amazon.com | Amazon.in)

Here's a screenshot of my notepad++ screen.