Regular Expressions 101

Explanation

Pro

^start of line

Non-Capturing Group(?:(?:\d+\.){2})?

?repeats the group contents below at most once:

Non-Capturing Group(?:\d+\.){2}

{2}repeats the group contents below exactly 2 times:

\d+a digit, repeated at least 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

Detailed match information will be displayed here automatically.

25 tokens

^(?:(?:\d+\.){2})?\d+$

New

1.22.33
3.44
12
1
7.77.55
8.88.88.99

1.22.33
3.44
12
1
7.77.55
8.88.88.99