How Can I Efficiently Extract Multiline C-Style Comments Using Regular Expressions?

Efficient Regex for Matching Multiline C-Style Comments

Extracting specific substrings from complex strings can be a challenging task. Users may encounter difficulties when attempting to remove multiline C-style comments from a given string using regular expressions.

To address this issue, consider employing the following optimized regex:

String pat = "/\*[^*]*\*+(?:[^/*][^*]*\*+)*/";

Breaking down the regex:

• /*: Matches the opening comment tag.
• ¹* : Matches zero or more non- characters followed by one or more literal *.

• (?:²¹* ): Captures zero or more repetitions of the following pattern:

  • ²¹¹* : Matches a character that is not / or , followed by zero or more non-asterisk characters, and then one or more asterisks.
• /*: Matches the closing comment tag.

This pattern effectively finds multiline comments by matching a sequence of non- characters enclosed within / and */, and handles nested comments by repeating the pattern as necessary.

Compared to alternative approaches, this regex operates more efficiently, matching multiline comments with significantly fewer steps. This enhanced efficiency minimizes the risk of potential stack overflow issues or similar performance bottlenecks.

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1. * ↩
2. /* ↩

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