Regular Expressions 101

Explanation

Pro

Non-Capturing Group(?:(?<=\S)( )+)?

?repeats the group contents below at most once:

Positive Lookbehind(?<=\S)

\Sany character that is not Unicode whitespace

Group 1( )+

+repeats the group contents below at least once:

the literal (32₁₀ / 40₈ / 20₁₆)

*the literal (32₁₀ / 40₈ / 20₁₆) , repeated any number of times

removethe literal text remove (case sensitive)

*the literal (32₁₀ / 40₈ / 20₁₆) , repeated any number of times

Condition(?(1) (?=\S)(?!remove\b))

Uses the first branch if group 1 matched

If the condition is true, match this branch: (?=\S)(?!remove\b)

the literal (32₁₀ / 40₈ / 20₁₆)

Positive Lookahead(?=\S)

\Sany character that is not Unicode whitespace

Negative Lookahead(?!remove\b)

removethe literal text remove (case sensitive)

\ba Unicode word boundary

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

Match Information

Detailed match information will be displayed here automatically.

Quick Reference

25 tokens

Regular Expression

(?:(?<=\S)( )+)? *remove *(?(1) (?=\S)(?!remove\b))

New

before remove after
before              remove      after
remove after
before remove
before     remove
remove
 remove 
remove 
before remove after remove before
before remove after remove before remove
before remove after remove before   remove   
before remove after remove before before      remove   remove remove
remove remove    remove

Extraction

before remove after
before              remove      after
remove after
before remove
before     remove
remove
 remove 
remove 
before remove after remove before
before remove after remove before remove
before remove after remove before   remove   
before remove after remove before before      remove   remove remove
remove remove    remove