On Tue, Apr 14, 2009 at 11:49, Rick <rich.j...@gmail.com> wrote:
> is it true that perl will be just as fast as c for reading files ?
>
> for example
>
> will below be as fast as if it were written in c?
> I said this because on random posts, I see that perl is optimized to work w/
> text files and it should be as fast as perl
>
> open FILE, $file or die "bad filename: $!";
> while (my $line = <FILE>) {
> #do something w $line
> }
snip
Why not test it?
With the file already in the filesystem's read-ahead buffer
cow...@amans:~$ time cat /usr/share/dict/words | perl wc.pl
234936
real 0m0.083s
user 0m0.062s
sys 0m0.015s
cow...@amans:~$ time cat /usr/share/dict/words | ./wc
234936
real 0m0.028s
user 0m0.013s
sys 0m0.012s
You can decide whether the .04 seconds is worth the extra time it
takes to write the C code.
#include <stdio.h>
int main (int argc, char** argv) {
char buf[4096];
size_t i;
size_t bytes;
size_t count = 0;
while (bytes = fread(buf, 1, 4096, stdin))
for (i = 0; i < bytes; i++)
if (buf[i] == '\n')
count++;
printf("%d\n", count);
return 0;
}
#!/usr/bin/perl
use strict;
use warnings;
my $count = 0;
$/ = \4096;
while (<>) {
$count += tr/\n//;
}
print "$count\n";
--
Chas. Owens
wonkden.net
The most important skill a programmer can have is the ability to read.
--
To unsubscribe, e-mail: beginners-unsubscr...@perl.org
For additional commands, e-mail: beginners-h...@perl.org
http://learn.perl.org/
