Regular Expressions 101

Pro

^start of line

Positive Lookahead(?=.+\.\d+\.)

.+any character (except for line terminators), repeated at least once

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

\d+a digit, repeated at least once

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

Negated Character Class[^.\n\r]+

+matches at least one character outside the set below:

.the literal . (46₁₀ / 56₈ / 2E₁₆)

\na line-feed (newline) character (ASCII 10)

\ra carriage return (ASCII 13)

Non-Capturing Group(?:\.[^.\n\r]+)+

+repeats the group contents below at least once:

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

Negated Character Class[^.\n\r]+

+matches at least one character outside the set below:

.the literal . (46₁₀ / 56₈ / 2E₁₆)

\na line-feed (newline) character (ASCII 10)

\ra carriage return (ASCII 13)

$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+\.)[^.\n\r]+(?:\.[^.\n\r]+)+$

aha.comment.1.app
aha.comment1.app

a.1.b.c.d.2.a
a.2.b.c2.a.1.