SPUG: Fw: greetings

[Russell Miller]

First thing and I screw up.  The message is below.  Thanks for your help.
----- Original Message -----
From: "Russell Miller" <duskglow2000 at yahoo.com>
To: <spug-list at perl.org>
Sent: Wednesday, October 17, 2001 8:13 PM
Subject: greetings


> Greetings all...  just joined the list, because I'm a professional perl
> programmer, and I have a problem I just can't seem to find the answer to,
> and I hope that you can help me out.  I'll try to help you guys (gals?)
out
> where I can, too.
>
> ok, we've got a six million line file to read.  I had written a program
that
> scaled just fine for smaller files, but it choked on this file, and took
an
> extreme amount of time.
>
> the original code goes like this:
>
> open (FILE, "<$INPUT");
> @array = <FILE>;
> close FILE;
>
> foreach $k (@array) {
>     ...
> }
>
> it worked just fine, but very slow and memory intensive for a six million
> line file.  So, we changed it to read sequentially:
>
> open (FILE, "<$input");
> foreach $k (<FILE>) {
>     ...
> }
>
> which got rid of the memory problem but the speed issue was still there.
So
> I changed the foreach line to:
>
> while ($k = <FILE>) {
>
> and the increase of speed had to be a thousand fold.
>
> What causes that speed impact?
>
> Thanks.
>
> --Russell
>


_________________________________________________________
Do You Yahoo!?
Get your free @yahoo.com address at http://mail.yahoo.com


 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     POST TO: spug-list at pm.org       PROBLEMS: owner-spug-list at pm.org
      Subscriptions; Email to majordomo at pm.org:  ACTION  LIST  EMAIL
  Replace ACTION by subscribe or unsubscribe, EMAIL by your Email-address
 For daily traffic, use spug-list for LIST ;  for weekly, spug-list-digest
     Seattle Perl Users Group (SPUG) Home Page: http://zipcon.net/spug/