Regular Expressions 101

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/
^[-+]?(\d{1,3})(,?(?1))*$
/
g
^ asserts position at start of the string
Match a single character present in the list below
[-+]
? matches the previous token between zero and one times, as many times as possible, giving back as needed (greedy)
- matches the character - with index 4510 (2D16 or 558) literally (case sensitive)
This hyphen is treated literally, which might be confusing for others. Consider escaping it or placing at the start or end of the class!
+ matches the character + with index 4310 (2B16 or 538) literally (case sensitive)
1st Capturing Group
(\d{1,3})
\d
matches a digit (equivalent to [0-9])
{1,3} matches the previous token between 1 and 3 times, as many times as possible, giving back as needed (greedy)
2nd Capturing Group
(,?(?1))*
* matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)
A repeated capturing group will only capture the last iteration. Put a capturing group around the repeated group to capture all iterations or use a non-capturing group instead if you're not interested in the data
,
matches the character , with index 4410 (2C16 or 548) literally (case sensitive)
(?1) recurses the 1st subpattern
$ asserts position at the end of the string, or before the line terminator right at the end of the string (if any)
Global pattern flags
g modifier: global. All matches (don't return after first match)
Your regular expression does not match the subject string.Try launching the debugger to find out why.

Regular Expression
No Match

/
/
g

Test String

Code Generator

Generated Code

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Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report.
For a full regex reference for Perl, please visit: http://perldoc.perl.org/perlre.html