Regular Expressions 101

Non-Capturing Group(?:^|\G)

1st Alternative^

^start of line

2nd Alternative\G

\Gstart of current search

Group 1(\d{1,3})

\d{1,3}a digit, repeated between 1 and 3 times

Positive Lookahead(?=(\d{3})+(?:\.\d+)?$)

Group 2(\d{3})+

+repeats the group contents below at least once:

\d{3}a digit, repeated exactly 3 times

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

?repeats the group contents below at most once:

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

\d+a digit, repeated at least once

$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

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Search reference

Regular Expression

(?:^|\G)(\d{1,3})(?=(\d{3})+(?:\.\d+)?$)

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