I'm desperately waiting for the second edition of Mastering Regular Expressions to come out. Until that time, there's a minor regex question that puzzles me.

In MRE, Friedl wrote that \d\d is more efficient than \d{2} because the second forces the re engine to count the occurences (thus incurring extra overhead) and the first simply allows it to match each in turn. However, it seems that this is a simple optimization. Does anyone know if this has happened in the newer versions of the re engine? I feel that \d{2} is more clear and generally use it, unless I am forced to optimize.

Cheers,
Ovid

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In reply to Regex optimizations by Ovid

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