Regular Expressions 101

Pro

^start of line

Positive Lookahead(?=(?:.+?\.){2,}.*$)

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

{2,}repeats the group contents below at least 2 times:

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

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

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

$end of line

Character Class[a-z]{1,2}

{1,2}matches between 1 and 2 characters from the set below:

a-zone character from a (97₁₀) to z (122₁₀) (case sensitive)

Non-Capturing Group(?:\.[a-z]{1,2})+

+repeats the group contents below at least once:

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

Character Class[a-z]{1,2}

{1,2}matches between 1 and 2 characters from the set below:

a-zone character from a (97₁₀) to z (122₁₀) (case sensitive)

$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

^(?=(?:.+?\.){2,}.*$)[a-z]{1,2}(?:\.[a-z]{1,2})+$

New

a.b.c.d
a.b
a.b.c
a.bb.c
aaa.bb.c
ab.c.dd.ee

a.b.c.d
a.b
a.b.c
a.bb.c
aaa.bb.c
ab.c.dd.ee