Regular Expressions 101

Non-Capturing Group(?:^|,\s*)

1st Alternative^

^start of line

2nd Alternative,\s*

,the literal , (44₁₀ / 54₈ / 2C₁₆)

\s*a Unicode whitespace character, repeated any number of times

Group 1(20\d\d(?:r\d+)?)

20the literal text 20

\da Unicode decimal digit

Non-Capturing Group(?:r\d+)?

?repeats the group contents below at most once:

rthe literal r (114₁₀ / 162₈ / 72₁₆) (case sensitive)

\d+a Unicode decimal digit, repeated at least once

Positive Lookahead(?=,|$)

1st Alternative,

,the literal , (44₁₀ / 54₈ / 2C₁₆)

2nd Alternative$

$end of line

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.

Search reference

Regular Expression

(?:^|,\s*)(20\d\d(?:r\d+)?)(?=,|$)

New

2018, \\\\some\\directory\\is\\here, \\\\some\\directory\\is\\here,  2019, \\\\here\\is\\another\\directory, \\\\here\\is\\another\\directory,  2021, \\\\here\\is\\another\\path_2021,   2020, http://some.will/even/look/like/this,   2022r2,   2023