Regular Expressions 101

Explanation

Pro

^start of line

Positive Lookahead(?=.*[ ]{2})

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

Character Class[ ]{2}

{2}matches exactly 2 characters from the set below:

the literal (32₁₀ / 40₈ / 20₁₆)

Negative Lookahead(?!.*[ ]{2}.*[ ]{2})

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

Character Class[ ]{2}

{2}matches exactly 2 characters from the set below:

the literal (32₁₀ / 40₈ / 20₁₆)

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

Character Class[ ]{2}

{2}matches exactly 2 characters from the set below:

the literal (32₁₀ / 40₈ / 20₁₆)

Group 1(.*)

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

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

^(?=.*[ ]{2})(?!.*[ ]{2}.*[ ]{2})(.*)

New

Line A:
foo bar  bar foo  bar foo
Line B:
foo bar  bar foo