Regular Expressions 101

^start of line

Negative Lookahead(?!.*\b(\d+)\b.*\b\1\b)

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

\ban ASCII word boundary

Group 1(\d+)

\d+a digit, repeated at least once

\ban ASCII word boundary

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

\ban ASCII word boundary

\1the text saved by group 1

\ban ASCII word boundary

\d+a digit, repeated at least once

Non-Capturing Group(?:,\d+)*

*repeats the group contents below any number of times:

,the literal , (44₁₀ / 54₈ / 2C₁₆)

\d+a digit, repeated at least once

$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

^(?!.*\b(\d+)\b.*\b\1\b)\d+(?:,\d+)*$

New

123
123,1234
1,2,45,4567

12,2343,12

,123,3444
,3344
12,3,,344
23,