Regular Expressions 101

^start of line

Negative Lookahead(?!000|666)

1st Alternative000

000the literal text 000

2nd Alternative666

666the literal text 666

Character Class[0-8]

0-8one character from 0 (48₁₀) to 8 (56₁₀)

Character Class[0-9]{2}

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

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

Group 1(-?)

-?optionally matches 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)

\1the text saved by group 1

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.

Search reference

Regular Expression

^(?!000|666)[0-8][0-9]{2}(-?)(?!00)[0-9]{2}\1(?!0000)[0-9]{4}$

123-26-4356
123264356