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in reply to what is the difference between index and rindex

fwiw, rindex appears to be slightly faster: 
use Benchmark qw(timethese);

my $s = "abcdefg";

timethese( 6_000_000,
    {
        rindex => sub { my $i = rindex( $s, "cde" ) },
         index => sub { my $i =  index( $s, "cde" ) },
    }
);

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Benchmark: timing 6000000 iterations of index, rindex...
index: 1 wallclock secs ( 1.14 usr + 0.00 sys = 1.14 CPU) @ 5263157.89/s (n=6000000)
rindex: 1 wallclock secs ( 1.02 usr + 0.00 sys = 1.02 CPU) @ 5882352.94/s (n=6000000)
their functional difference is that rindex starts from the end of the string, and index starts at the beginning. there is no difference in their usage.

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Re^2: what is the difference between index and rindex
by ikegami (Patriarch) on Sep 06, 2006 at 16:05 UTC

    For me, index is faster. In any case the difference is less than 10% (for both me and you), so the test is not conclusive. ( Even if it were conclusive, the difference is rather minor. Of course, this is all moot since the two functions are not interchangeable. )

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