Regular Expressions 101

Pro

Non-Capturing Group(?:\G(?!^)|^(?=.*string3))

1st Alternative\G(?!^)

\Gstart of current search

Negative Lookahead(?!^)

^start of line

2nd Alternative^(?=.*string3)

^start of line

Positive Lookahead(?=.*string3)

.*any character (except for line terminators), repeated any number of times

string3the literal text string3 (case sensitive)

.*?any character (except for line terminators), repeated any number of times

\Kresets the starting point of the reported match. Any previously consumed characters are no longer included in the final match

string1the literal text string1 (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

Regular Expression

(?:\G(?!^)|^(?=.*string3)).*?\Kstring1

New

This is line string1
This is line two with string1 and string3 string1
This is line two with string1 string1 and string3 
This is line three with string3
This is line string3 with string1 and string1

Substitution

string2

This is line string1
This is line two with string1 and string3 string1
This is line two with string1 string1 and string3 
This is line three with string3
This is line string3 with string1 and string1