Regular Expressions 101

^start of line

Negative Lookahead(?!123([ -]?)45([ -]?)6789)

123the literal text 123

Group 1([ -]?)

Character Class[ -]?

?matches at most one character from the set below:

the literal (32₁₀ / 40₈ / 20₁₆)

-the literal - (45₁₀ / 55₈ / 2D₁₆)

45the literal text 45

Group 2([ -]?)

Character Class[ -]?

?matches at most one character from the set below:

the literal (32₁₀ / 40₈ / 20₁₆)

-the literal - (45₁₀ / 55₈ / 2D₁₆)

6789the literal text 6789

Negative Lookahead(?!\b(\d)\3+\b)

\ban ASCII word boundary

Group 3(\d)

\da digit

\3+the text saved by group 3, repeated at least once

\ban ASCII word boundary

Negative Lookahead(?!000|666|900|999)

1st Alternative000

000the literal text 000

2nd Alternative666

666the literal text 666

3rd Alternative900

900the literal text 900

4th Alternative999

999the literal text 999

Character Class[0-9]{3}

{3}matches exactly 3 characters from the set below:

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

Group 4([ -]?)

Character Class[ -]?

?matches at most one character from the set below:

the literal (32₁₀ / 40₈ / 20₁₆)

-the literal - (45₁₀ / 55₈ / 2D₁₆)

Negative Lookahead(?!00)

00the literal text 00

Character Class[0-9]{2}

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

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

\4the text saved by group 4

Negative Lookahead(?!0000)

0000the literal text 0000

Character Class[0-9]{4}

{4}matches exactly 4 characters from the set below:

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

$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.

26 tokens

Regular Expression

^(?!123([ -]?)45([ -]?)6789)(?!\b(\d)\3+\b)(?!000|666|900|999)[0-9]{3}([ -]?)(?!00)[0-9]{2}\4(?!0000)[0-9]{4}$

New

899-45-6789
001-23-4567
232456789
232 45 6789
123456780
123-45-6780

123456789
123 45 6789
123-45-6789
111111111
111-11-1111
422-12 1212
12345 6789
123 456789
123x45x6789
ABCDEEEEE
1234567890123
000-45-6789
123-00-6789
123-45-0000
666-45-6789

Regular Expression

Substitution