Regular Expressions 101

Pro

Positive Lookbehind(?<=\.)

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

Group 1([^.]+)

Negated Character Class[^.]+

+matches at least one character outside the set below:

.the literal . (46₁₀ / 56₈ / 2E₁₆)

Non-Capturing Group(?:\.(?:co\.uk|ac\.us|[^.]+(?:$|\n)))

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

Non-Capturing Group(?:co\.uk|ac\.us|[^.]+(?:$|\n))

1st Alternativeco\.uk

cothe literal text co (case sensitive)

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

ukthe literal text uk (case sensitive)

2nd Alternativeac\.us

acthe literal text ac (case sensitive)

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

usthe literal text us (case sensitive)

3rd Alternative[^.]+(?:$|\n)

Negated Character Class[^.]+

+matches at least one character outside the set below:

.the literal . (46₁₀ / 56₈ / 2E₁₆)

Non-Capturing Group(?:$|\n)

1st Alternative$

$end of string, or before its final line terminator

2nd Alternative\n

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

Global pattern flags

g modifier: global. Finds all matches instead of stopping after the first

Detailed match information will be displayed here automatically.

25 tokens

Regular Expression

(?<=\.)([^.]+)(?:\.(?:co\.uk|ac\.us|[^.]+(?:$|\n)))

New

m.google.com
m.docs.google.com
www.someisotericdomain.innersite.mall.co.uk
www.ouruniversity.department.mit.ac.us
www.somestrangeurl.shops.relevantdomain.net
www.example.info

Extraction

m.google.com
m.docs.google.com
www.someisotericdomain.innersite.mall.co.uk
www.ouruniversity.department.mit.ac.us
www.somestrangeurl.shops.relevantdomain.net
www.example.info