Regular Expressions 101

Pro

\ban ASCII word boundary

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

{3}repeats the group contents below exactly 3 times:

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

Character Class[ -]?

?matches at most one character from the set below:

the literal (32₁₀ / 40₈ / 20₁₆)

-the literal - (45₁₀ / 55₈ / 2D₁₆)

Positive Lookahead(?=\d{4}\b)

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

\ban ASCII word boundary

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.

26 tokens

Regular Expression

\b(?:\d{4}[ -]?){3}(?=\d{4}\b)

New

Hi here is my card number its visa 4242 4242 4242 4242
Hi here is my card number its visa 4242424242424242
Hi here is my card number its visa 4242-4242-4242-4242

Extraction

Hi here is my card number its visa 4242 4242 4242 4242
Hi here is my card number its visa 4242424242424242
Hi here is my card number its visa 4242-4242-4242-4242