Regular Expressions 101

Explanation

Pro

Negative Lookbehind(?<!My )

My the literal text My (case sensitive)

\ban ASCII word boundary

Item 1the literal text Item 1 (case sensitive)

\ban ASCII word boundary

Negative Lookahead(?! Test)

Testthe literal text Test (case sensitive)

Global pattern flags

g modifier: global. Finds all matches instead of stopping after the first

m modifier: multiline. Causes ^ and $ to match the start and end of each line, not only the start and end of the string

Detailed match information will be displayed here automatically.

25 tokens

(?<!My )\bItem 1\b(?! Test)

Remove this Item 1, but not My Item 1, Item 1 Test, nor Item 11, Item 12 just for fun

Only Item 11 left due to the promotion on Item 1

Something

Remove this Item 1, but not My Item 1, Item 1 Test, nor Item 11, Item 12 just for fun

Only Item 11 left due to the promotion on Item 1