Regular Expressions 101

Pro

^start of line

Negative Lookahead(?!.*(\d)(?:-*\1){3})

.*any character (except for line terminators), repeated any number of times

Group 1(\d)

\da digit

Non-Capturing Group(?:-*\1){3}

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

-*the literal - (45₁₀ / 55₈ / 2D₁₆) , repeated any number of times

\1the text saved by group 1

.*any character (except for line terminators), repeated any number of times

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

^(?!.*(\d)(?:-*\1){3}).*

New

1234-5678-9101-1213
1233-3345-6789-1011

1234-5678-9101-1213
1233-3345-6789-1011