How to Match Consecutive Repetitive Characters with Regular Expressions?

Matching Repetitive Characters with Regular Expressions

When attempting to construct a regex that identifies strings with three or more consecutive repetitive characters, common approaches such as "[A-Za-z0-9]{3,}", "(.)1{3,}", and "(.){3,}" may prove insufficient. These expressions match any three repetitive characters in order, but not necessarily contiguous ones.

The Challenge of Consecutive Matches

The inability to match consecutive characters stems from the limitations of true regular expressions. Backreferences, which enable matching a previously matched string or subsequence, are not inherently supported in traditional regular expression implementations like RE2 used by Go. The absence of backreferences limits the capability of regex engines to perform such specific character sequences.

Alternative Solutions

Given these limitations, several alternatives are available:

• External Regex Libraries: Exploring other regex libraries such as PCRE bindings may provide the necessary backreference functionality.
• Custom String Parsing: Manually parsing the string without relying on regex expressions offers another approach to identifying consecutive repetitive characters.

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