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Re: Re: Re: Regex matching on anywhere but the beginning or end of a line

by fruiture (Curate)
on Feb 23, 2003 at 12:51 UTC ( #237884=note: print w/ replies, xml ) Need Help??


in reply to Re: Re: Regex matching on anywhere but the beginning or end of a line
in thread Regex matching on anywhere but the beginning or end of a line

Although I agree that probably a regexp is more straight-forward, I get different results benchmarking the stuff.

my $string = q{"string (12" or 1 foot or 1') into 6" MySQL varchar"}; benchmark( shift, q{"string (12"" or 1 foot or 1') into 6"" MySQL varchar"}, 'substr' => sub { my $t = $string; substr($t, 1, -1) =~ s/"/""/g; $t }, 's///' => sub { my $t = $string; $t =~ s/(?<=.)"(?=.)/""/g; $t }, 'index' => sub { my $t = $string; local $_ = 1; while( ($_ = index($t,'"',$_)) !=-1 and ++$_ < length($t) ){ substr($t,$_++,0,'"'); } $t }, );

benchmark() is just a wrapper around Benchmark::cmpthese() that checks the results of the routines.

# run with perl 5.6.1 EXPECTED : "string (12"" or 1 foot or 1') into 6"" MySQL varchar" index : "string (12"" or 1 foot or 1') into 6"" MySQL varchar" s/// : "string (12"" or 1 foot or 1') into 6"" MySQL varchar" substr : "string (12"" or 1 foot or 1') into 6"" MySQL varchar" Benchmark: timing 1000000 iterations of index , s/// , subs +tr ... index : 19 wallclock secs (19.66 usr + 0.02 sys = 19.68 CPU) @ 5 +0813.01/s (n=1000000) s/// : 19 wallclock secs (19.85 usr + 0.00 sys = 19.85 CPU) @ 5 +0377.83/s (n=1000000) substr : 23 wallclock secs (24.13 usr + 0.00 sys = 24.13 CPU) @ 4 +1442.19/s (n=1000000) Rate substr s/// index substr 41442/s -- -18% -18% s/// 50378/s 22% -- -1% index 50813/s 23% 1% -- # and with perl 5.8.0 EXPECTED : "string (12"" or 1 foot or 1') into 6"" MySQL varchar" substr : "string (12"" or 1 foot or 1') into 6"" MySQL varchar" index : "string (12"" or 1 foot or 1') into 6"" MySQL varchar" s/// : "string (12"" or 1 foot or 1') into 6"" MySQL varchar" Benchmark: timing 1000000 iterations of index , s/// , subs +tr ... index : 18 wallclock secs (18.71 usr + 0.01 sys = 18.72 CPU) @ 5 +3418.80/s (n=1000000) s/// : 33 wallclock secs (31.67 usr + 0.02 sys = 31.69 CPU) @ 3 +1555.70/s (n=1000000) substr : 35 wallclock secs (35.24 usr + 0.01 sys = 35.25 CPU) @ 2 +8368.79/s (n=1000000) Rate substr s/// index substr 28369/s -- -10% -47% s/// 31556/s 11% -- -41% index 53419/s 88% 69% --
--
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Re: Re: Re: Re: Regex matching on anywhere but the beginning or end of a line
by xmath (Hermit) on Feb 23, 2003 at 13:09 UTC
    Okay, I re-ran the benchmark with your exact code on my computer, and I got:

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