Regular Expressions 101

Pro

^start of line

Positive Lookahead(?=(?:[^\n\d]*\d){4})

Non-Capturing Group(?:[^\n\d]*\d){4}

{4}repeats the group contents below exactly 4 times:

Negated Character Class[^\n\d]*

*matches any number of characters outside the set below:

\na line-feed (newline) character (ASCII 10)

\da digit

Character Class[-0-9_,/\s]+

+matches at least one character from the set below:

-the literal - (45₁₀ / 55₈ / 2D₁₆)

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

_the literal _ (95₁₀ / 137₈ / 5F₁₆)

,the literal , (44₁₀ / 54₈ / 2C₁₆)

/the literal / (47₁₀ / 57₈ / 2F₁₆)

\sany whitespace character

$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

^(?=(?:[^\n\d]*\d){4})[-0-9_,/\s]+$

New

1,2
3/5/6
7-8-9

09-12345678
123, 456, 789
12/ 34/ 56

1,2
3/5/6
7-8-9

09-12345678
123, 456, 789
12/ 34/ 56