Using regex to find arbitrary length consecutive blocks

Question

I have a string containing ones and zeroes. I want to determine if there are substrings of 1 or more characters that are repeated at least 3 consecutive times. For example, the string '000' has a length 1 substring consisting of a single zero character that is repeated 3 times. The string '010010010011' actually has 3 such substrings that each are repeated 3 times ('010', '001', and '100').

Is there a regex expression that can find these repeating patterns without knowing either the specific pattern or the pattern's length? I don't care what the pattern is nor what its length is, only that the string contains a 3-peat pattern.

Answer 1

Here's something that might work, however, it will only tell you if there is a pattern repeated three times, and (I don't think) can't be extended to tell you if there are others:

     /(.+).*?\1.*?\1/

Breaking that out:

   (.+)          matches any 1 or more characters, starting anywhere in the string
   .*?           allows any length of interposing other characters (0 or more)
   \1            matches whatever was captured by the (...+) parentheses
   .*?           0 or more of anything
   \1            the original pattern, again

If you want the repetitions to occur immediately adjacent, then instead use

     /(.+)\1\1/

… as suggested by @Buh Buh — the \1 vs. $1 notation may vary, depending on your regexp system.

Answer 2

(.+)\1\1

The \ might be a different charactor depending on your language choice. This means match any string then try to match it again twice more.

The \1 means repeat the 1st match.