Regular Expressions 101

Pro

^start of line

Positive Lookahead(?=[\d-]{5})

Character Class[\d-]{5}

{5}matches exactly 5 characters from the set below:

\da digit

-the literal - (45₁₀ / 55₈ / 2D₁₆)

Atomic Group(?>\d+-*|-{5})

1st Alternative\d+-*

\d+a digit, repeated at least once

-*the literal - (45₁₀ / 55₈ / 2D₁₆) , repeated any number of times

2nd Alternative-{5}

-{5}the literal - (45₁₀ / 55₈ / 2D₁₆) , repeated exactly 5 times

Character Class[A-Z\d_]*

*matches any number of characters from the set below:

A-Zone character from A (65₁₀) to Z (90₁₀) (case sensitive)

\da digit

_the literal _ (95₁₀ / 137₈ / 5F₁₆)

$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-]{5})(?>\d+-*|-{5})[A-Z\d_]*$

New

12345ABC
12345123
1234-1
1234--1
1----1AB
123----
-----

123A----
-2-2-
1AAAAAA
1-2-3-A
----1AB
--1--1A

12345ABC
12345123
1234-1
1234--1
1----1AB
123----
-----

123A----
-2-2-
1AAAAAA
1-2-3-A
----1AB
--1--1A