regex101: PCRE (Legacy) Match Workspace

^start of line

Non-Capturing Group(?:(?>([a-f0-9]{1,4})(?>:(?1)){7}|(?!(?:.*[a-f0-9](?>:|$)){8,})((?1)(?>:(?1)){0,6})?::(?2)?)|(?>(?>(?1)(?>:(?1)){5}:|(?!(?:.*[a-f0-9]:){6,})(?3)?::(?>((?1)(?>:(?1)){0,4}):)?)?(25[0-5]|2[0-4][0-9]|1[0-9]{2}|[1-9]?[0-9])(?>\.(?4)){3}))

1st Alternative(?>([a-f0-9]{1,4})(?>:(?1)){7}|(?!(?:.*[a-f0-9](?>:|$)){8,})((?1)(?>:(?1)){0,6})?::(?2)?)

Atomic Group(?>([a-f0-9]{1,4})(?>:(?1)){7}|(?!(?:.*[a-f0-9](?>:|$)){8,})((?1)(?>:(?1)){0,6})?::(?2)?)

1st Alternative([a-f0-9]{1,4})(?>:(?1)){7}

Group 1([a-f0-9]{1,4})

Character Class[a-f0-9]{1,4}

{1,4}matches between 1 and 4 characters from the set below:

a-fone character from a (97₁₀) to f (102₁₀) (case insensitive)

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

Atomic Group(?>:(?1)){7}

{7}repeats the group contents below exactly 7 times:

:the literal : (58₁₀ / 72₈ / 3A₁₆)

(?1)calls group 1 as a subroutine

2nd Alternative(?!(?:.*[a-f0-9](?>:|$)){8,})((?1)(?>:(?1)){0,6})?::(?2)?

Negative Lookahead(?!(?:.*[a-f0-9](?>:|$)){8,})

Non-Capturing Group(?:.*[a-f0-9](?>:|$)){8,}

{8,}repeats the group contents below at least 8 times:

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

Character Class[a-f0-9]

a-fone character from a (97₁₀) to f (102₁₀) (case insensitive)

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

Atomic Group(?>:|$)

1st Alternative:

:the literal : (58₁₀ / 72₈ / 3A₁₆)

2nd Alternative$

$end of line

Group 2((?1)(?>:(?1)){0,6})?

?repeats the group contents below at most once:

(?1)calls group 1 as a subroutine

Atomic Group(?>:(?1)){0,6}

{0,6}repeats the group contents below between 0 and 6 times:

:the literal : (58₁₀ / 72₈ / 3A₁₆)

(?1)calls group 1 as a subroutine

::the literal text ::

(?2)?optionally calls group 2 as a subroutine

2nd Alternative(?>(?>(?1)(?>:(?1)){5}:|(?!(?:.*[a-f0-9]:){6,})(?3)?::(?>((?1)(?>:(?1)){0,4}):)?)?(25[0-5]|2[0-4][0-9]|1[0-9]{2}|[1-9]?[0-9])(?>\.(?4)){3})

Atomic Group(?>(?>(?1)(?>:(?1)){5}:|(?!(?:.*[a-f0-9]:){6,})(?3)?::(?>((?1)(?>:(?1)){0,4}):)?)?(25[0-5]|2[0-4][0-9]|1[0-9]{2}|[1-9]?[0-9])(?>\.(?4)){3})

Atomic Group(?>(?1)(?>:(?1)){5}:|(?!(?:.*[a-f0-9]:){6,})(?3)?::(?>((?1)(?>:(?1)){0,4}):)?)?

?repeats the group contents below at most once:

1st Alternative(?1)(?>:(?1)){5}:

(?1)calls group 1 as a subroutine

Atomic Group(?>:(?1)){5}

{5}repeats the group contents below exactly 5 times:

:the literal : (58₁₀ / 72₈ / 3A₁₆)

(?1)calls group 1 as a subroutine

:the literal : (58₁₀ / 72₈ / 3A₁₆)

2nd Alternative(?!(?:.*[a-f0-9]:){6,})(?3)?::(?>((?1)(?>:(?1)){0,4}):)?

Negative Lookahead(?!(?:.*[a-f0-9]:){6,})

Non-Capturing Group(?:.*[a-f0-9]:){6,}

{6,}repeats the group contents below at least 6 times:

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

Character Class[a-f0-9]

a-fone character from a (97₁₀) to f (102₁₀) (case insensitive)

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

:the literal : (58₁₀ / 72₈ / 3A₁₆)

(?3)?optionally calls group 3 as a subroutine

::the literal text ::

Atomic Group(?>((?1)(?>:(?1)){0,4}):)?

Group 4(25[0-5]|2[0-4][0-9]|1[0-9]{2}|[1-9]?[0-9])

Atomic Group(?>\.(?4)){3}

$end of line

Global pattern flags

i modifier: insensitive. Matches without distinguishing uppercase and lowercase letters

m modifier: multiline. Causes ^ and $ to match the start and end of each line, not only the start and end of the string

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

D modifier: Dollar. Forces $ to match only at the end of the string instead of also before a final line terminator. This option is ignored if the m-flag is set

Search reference

Regular Expression

^(?:(?>([a-f0-9]{1,4})(?>:(?1)){7}|(?!(?:.*[a-f0-9](?>:|$)){8,})((?1)(?>:(?1)){0,6})?::(?2)?)|(?>(?>(?1)(?>:(?1)){5}:|(?!(?:.*[a-f0-9]:){6,})(?3)?::(?>((?1)(?>:(?1)){0,4}):)?)?(25[0-5]|2[0-4][0-9]|1[0-9]{2}|[1-9]?[0-9])(?>\.(?4)){3}))$

New

/*These should be valid*/

{Initial address}
2001:0db8:0000:0000:0000:ff00:0042:8329

{After removing all leading zeroes}
2001:db8:0:0:0:ff00:42:8329

{After omitting consecutive sections of zeroes}
2001:db8::ff00:42:8329

{The loopback address}
0000:0000:0000:0000:0000:0000:0000:0001

{The loopback address be abbreviated to ::1 by using both rules}
::1

{4 other valid test cases}
::FFFF:129.144.52.38
::129.144.52.38
::FFFF:d
1080:0:0:0:8:800:200C:417A

/*These 4 should be invalid*/
::FFFF:d.d.d
::FFFF:d.d
::d.d.d
::d.d

Regular Expressions 101

Regular Expression

Substitution