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Asked: 2026-05-11T06:10:52+00:00

I’m parsing some big log files and have some very simple string matches for

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I’m parsing some big log files and have some very simple string matches for example

if(m/Some String Pattern/o){     #Do something }

It seems simple enough but in fact most of the matches I have could be against the start of the line, but the match would be ‘longer’ for example

if(m/^Initial static string that matches Some String Pattern/o){     #Do something }

Obviously this is a longer regular expression and so more work to match. However I can use the start of line anchor which would allow an expression to be discarded as a failed match sooner.

It is my hunch that the latter would be more efficient. Can any one back me up/shoot me down 🙂

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1 Answer

  1. I think you’ll find that starting your regex with ^ will definitely be faster, because the regex engine doesn’t have to look any further than the left edge of the string for a match.

    This is something that you could easily test and measure, of course. Do a regex match 10 million times or so, measure how long it takes, then try again with a different regex.

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