Regular Expressions 101

Explanation

Pro

^start of line

GBthe literal text GB (case sensitive)

Non-Capturing Group(?:\d{3} ?\d{4} ?\d{2}(?:\d{3})?|[A-Z]{2}\d{3})

1st Alternative\d{3} ?\d{4} ?\d{2}(?:\d{3})?

\d{3}a digit, repeated exactly 3 times

?optionally matches the literal (32₁₀ / 40₈ / 20₁₆)

\d{4}a digit, repeated exactly 4 times

?optionally matches the literal (32₁₀ / 40₈ / 20₁₆)

\d{2}a digit, repeated exactly 2 times

Non-Capturing Group(?:\d{3})?

?repeats the group contents below at most once:

\d{3}a digit, repeated exactly 3 times

2nd Alternative[A-Z]{2}\d{3}

Character Class[A-Z]{2}

{2}matches exactly 2 characters from the set below:

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

\d{3}a digit, repeated exactly 3 times

$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

^GB(?:\d{3} ?\d{4} ?\d{2}(?:\d{3})?|[A-Z]{2}\d{3})$

New

GB999999973
GBGD001
GBHA599
GB999 9999 73

GB999999973
GBGD001
GBHA599
GB999 9999 73