Regular Expressions 101

Explanation

Pro

^start of line

Non-Capturing Group(?:(?'protocol'[a-z]{2,}(?=[:])):)?

?repeats the group contents below at most once:

Group protocol(?'protocol'[a-z]{2,}(?=[:]))

Character Class[a-z]{2,}

{2,}matches at least 2 characters from the set below:

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

Positive Lookahead(?=[:])

Character Class[:]

:the literal : (58₁₀ / 72₈ / 3A₁₆)

Non-Capturing Group(?:\/\/)?

?repeats the group contents below at most once:

\/the literal / (47₁₀ / 57₈ / 2F₁₆)

Non-Capturing Group(?:(?'subdomain'(?:[0-9a-z](?![\-\.]))+(?:[0-9a-z\-\.][0-9a-z]+)+?)\.(?'domain'(?:[0-9a-z](?![\-]))+(?:[0-9a-z\-][0-9a-z])\.(?'tld'[a-z]{2,}(?:\.[a-z]{2})?))|(?'ip'(?'segment'[01][0-9][0-9]|2[0-4][0-9]|25[0-5]|[0-9])\.(?&segment)\.(?&segment)\.(?&segment)))

1st Alternative(?'subdomain'(?:[0-9a-z](?![\-\.]))+(?:[0-9a-z\-\.][0-9a-z]+)+?)\.(?'domain'(?:[0-9a-z](?![\-]))+(?:[0-9a-z\-][0-9a-z])\.(?'tld'[a-z]{2,}(?:\.[a-z]{2})?))

Group subdomain(?'subdomain'(?:[0-9a-z](?![\-\.]))+(?:[0-9a-z\-\.][0-9a-z]+)+?)

Non-Capturing Group(?:[0-9a-z](?![\-\.]))+

+repeats the group contents below at least once:

Character Class[0-9a-z]

0-9one character from 0 (48₁₀) to 9 (57₁₀)

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

Negative Lookahead(?![\-\.])

Character Class[\-\.]

\-the literal - (45₁₀ / 55₈ / 2D₁₆)

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

Non-Capturing Group(?:[0-9a-z\-\.][0-9a-z]+)+?

+?repeats the group contents below at least once:

Character Class[0-9a-z\-\.]

0-9one character from 0 (48₁₀) to 9 (57₁₀)

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

\-the literal - (45₁₀ / 55₈ / 2D₁₆)

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

Character Class[0-9a-z]+

+matches at least one character from the set below:

0-9one character from 0 (48₁₀) to 9 (57₁₀)

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

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

Group domain(?'domain'(?:[0-9a-z](?![\-]))+(?:[0-9a-z\-][0-9a-z])\.(?'tld'[a-z]{2,}(?:\.[a-z]{2})?))

Non-Capturing Group(?:[0-9a-z](?![\-]))+

+repeats the group contents below at least once:

Character Class[0-9a-z]

0-9one character from 0 (48₁₀) to 9 (57₁₀)

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

Negative Lookahead(?![\-])

Character Class[\-]

\-the literal - (45₁₀ / 55₈ / 2D₁₆)

Non-Capturing Group(?:[0-9a-z\-][0-9a-z])

Character Class[0-9a-z\-]

0-9one character from 0 (48₁₀) to 9 (57₁₀)

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

\-the literal - (45₁₀ / 55₈ / 2D₁₆)

Character Class[0-9a-z]

0-9one character from 0 (48₁₀) to 9 (57₁₀)

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

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

Group tld(?'tld'[a-z]{2,}(?:\.[a-z]{2})?)

Character Class[a-z]{2,}

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

2nd Alternative(?'ip'(?'segment'[01][0-9][0-9]|2[0-4][0-9]|25[0-5]|[0-9])\.(?&segment)\.(?&segment)\.(?&segment))

Non-Capturing Group(?:\:(?'port'\d+))?

Group path(?'path'(?:\/[^\/\?]*?)*)?

Non-Capturing Group(?:\?(?'query'[^#]*))?

Non-Capturing Group(?:#!?(?'hash'.*))?

$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

Match Information

Detailed match information will be displayed here automatically.

Quick Reference

25 tokens

Regular Expression

^(?:(?'protocol'[a-z]{2,}(?=[:])):)?(?:\/\/)?(?:(?'subdomain'(?:[0-9a-z](?![\-\.]))+(?:[0-9a-z\-\.][0-9a-z]+)+?)\.(?'domain'(?:[0-9a-z](?![\-]))+(?:[0-9a-z\-][0-9a-z])\.(?'tld'[a-z]{2,}(?:\.[a-z]{2})?))|(?'ip'(?'segment'[01][0-9][0-9]|2[0-4][0-9]|25[0-5]|[0-9])\.(?&segment)\.(?&segment)\.(?&segment)))(?:\:(?'port'\d+))?(?'path'(?:\/[^\/\?]*?)*)?(?:\?(?'query'[^#]*))?(?:#!?(?'hash'.*))?$

ftp://regex101.billy.com.uk:3000/test/blah?hello=blah&#!/blah/blue/green
https://192.168.1.1/test/lab

Substitution

ftp://regex101.billy.com.uk:3000/test/blah?hello=blah&#!/blah/blue/green
https://192.168.1.1/test/lab