Beefy Boxes and Bandwidth Generously Provided by pair Networks
Don't ask to ask, just ask
 
PerlMonks  

Re: Fast Identification Of String Difference

by educated_foo (Vicar)
on Jan 18, 2011 at 03:09 UTC ( #882802=note: print w/ replies, xml ) Need Help??


in reply to Fast Identification Of String Difference

I was curious, so...

use Inline C; sub cmp_perl { my ($a, $b) = @_; my $c = $a ^ $b; my @ret; push @ret, pos($c) while $c =~ /[^\0]/g; @ret; } use Benchmark ':all'; my ($x, $y); $y = $x = 'A' x 1e6; substr($y, $_*100, 1) = 'C' for 1..(1e4-1); timethese(0, { perl => sub { cmp_perl($x, $y); }, C => sub { cmp_c($x, $y); }, }); __END__ __C__ void cmp_c(char *a, char *b) { int i, n; Inline_Stack_Vars; Inline_Stack_Reset; for (i=0, n=0; *a && *b; a++, b++, i++) if (*a != *b) mXPUSHi(i), n++; Inline_Stack_Return(n); }
I was disappointed that the Perl version was about 8x slower:
Benchmark: running C, perl for at least 3 CPU seconds... C: 3 wallclock secs ( 3.17 usr + 0.00 sys = 3.17 CPU) @ 37 +9.18/s (n=1202) perl: 3 wallclock secs ( 3.17 usr + 0.00 sys = 3.17 CPU) @ 43 +.22/s (n=137)


Comment on Re: Fast Identification Of String Difference
Select or Download Code

Log In?
Username:
Password:

What's my password?
Create A New User
Node Status?
node history
Node Type: note [id://882802]
help
Chatterbox?
and the web crawler heard nothing...

How do I use this? | Other CB clients
Other Users?
Others romping around the Monastery: (12)
As of 2015-07-30 14:27 GMT
Sections?
Information?
Find Nodes?
Leftovers?
    Voting Booth?

    The top three priorities of my open tasks are (in descending order of likelihood to be worked on) ...









    Results (271 votes), past polls