I use a regex to validate number formats.
[-+]?([0-90-9]+((\,([0-90-9]{2,}))*\,([0-90-9]{3}))*)?(\.[0-90-9]*)?
When I handled a large number of inputs for certain inputs it seems to loop infinitely .I read other answers regarding catastrophic backtracking . But I am a regex newbie and need some help. can you please provide any input that can make this regex catastrophically backtrack . Would be helpful for me to understand .Thanks .It can be a very long input too . I am using Java Pattern and matcher objects.
Yes, this regex is prone to catastrophic backtracking. Specifically, this segment:
((\,([0-9]{2,}))*\,([0-9]{3}))*
For reference, this has a structure of the form
((,d)*,d)*
which, simplified, is essentially (d+)*.
Strings like
1,111,111,111,111,111,111,111,111,111,111,111,111,111,11.
will therefore cause catastrophic backtracking.