Date: Mon, 16 Jul 2001 17:27:38 +0100
From: Jasper McCrea <jmccrea@guideguide.com>
To: Wali Haidri <whaidri@ford.com>
Subject: Re: ARRAYS: find common values
Message-Id: <3B5315FA.44B1AC12@guideguide.com>

Wali Haidri wrote:
> 
> I want to out put the common values in the two arrays below. Following
> code does work but it is very slow.  I hope somebody can suggest a
> better way.

isn't this an FAQ. ie use a hash.

# haven't tested this, and am assuming (probably correctly :) )
# that uc works on $_
my %users2 = map { uc => 1 } @users2;

foreach my $user (sort { $a cmp $b} map { uc } @users) {
  push @finalusers, $user if $users2{$user};
}

return @finalusers;

probably you'll find that this isn't much faster. 
But it isn't what perl was designed to do, I guess.

I also not that you're using next LINE when the code doesn't do anything
afterward, anyway. There's only a necessity to put a next in if there's
more code you want to avoid.

I have also uc'd all values straight away. You waste time by testing
against a uced $val1 (this ucing being done every time), and then if you
actually want to use it, you uc it anyway.

You're also declaring variables that only need a small scope with a much
larger scope ($val1, $val2).

Jasper

> 
> sub get_usersByToken3{
> 
> # my (@users) defined somewhere else and has a list of users.
> # my (users2) " "  "  "  "
> my (@finalusers);
> my ($tval, $val1, $val2);
> 
> # FIRST SORT BOTH ARRAYS
> 
>         @users          = sort { uc($a) cmp uc($b) } @users;
>         @users2         = sort { uc($a) cmp uc($b) } @users2;
> 
> # NOW FOR EACH ELEMENT IN LIST 1, TRY TO FIND IT IN LIST 2. IF FOUND
> # PUSH IT TO AN OUTPUT ARRAY AND EXIT OUT OF THIS LOOK BACK TO THE FIRST
> # foreach LOOP.
> 
> LINE:
>   foreach $val1 (@users){
>      foreach $val2 (@users2){
>         if ( $val2  eq uc($val1) ) {
>                 push(@finalusers, uc($val1));
>         next LINE;
>         }
>     }
>   } # end of foreach
> return (@finalusers);
> }
> 
> Please cc to my email address if possible.  Thanks.
> 
> Wali Haidri
> whaidri@ford.com

-- 
      split//,'019617511192'.
      '17011111610114101114'.
      '21011141011840799901'.
            '17101174';
            foreach(0..
            $#_){$_[$_
            ++]^=$_[$_
            --]^=$_[$_
]^=$_[++    $_]if!($_%
2)}$g.=$_  ,chr($g)=~
 /(\w)/&&($o.=$1and
   $g='')foreach@_;
      print"$o\n"