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return value from function

webhay
Novice

Jan 1, 2003, 10:01 AM

Post #1 of 5 (2569 views)

return value from function	Can't Post

i made function that generate random NUmber and letter but i want it to return the random number.

sub gensid {
@alpha=("q","w","e","r","t","y","u","i","o","p","l","k","j","h","g","f","d","s","a","m","n",
"b","v","c","x","z","6","7","8","9","0","5","4","3","2","1","z");

for($i=0; $i<32; $i++) {
$letter = (int(rand $#alpha));
$sid = $alpha[$letter];
}

}

i need to get the value like this:
$sid = &gensid;

thanks
webhay

Jasmine
Administrator / Moderator

Jan 1, 2003, 10:31 AM

Post #2 of 5 (2564 views)

Re: [webhay] return value from function [In reply to]	Can't Post

To answer your question....

Code

sub gensid {  
    my $sid = ''; 
    my @alpha= qw/ q w e r t y u i o p l k j h g f d s 
                   a m n b v c x z 6 7 8 9 0 5 4 3 2 1 / ; 
 
    $sid .= $alpha[ int rand @alpha ] for 1 .. 32; 
    return $sid; 
} 
 
my $sid = gensid();

But I recommend using either [url=http://search.cpan.org/author/SHERZODR/CGI-Session-3.11/]CGI::Session or one of options shown below instead of just using random characters to create session ids (I'm assuming you're creating session ids because of the $sid).

From CGI Programming with Perl:

Code

use Digest::MD5; 
 
my $md5    = new Digest::MD5; 
my $remote = $ENV{REMOTE_ADDR} . $ENV{REMOTE_PORT}; 
my $id     = $md5->md5_base64( time, $$, $remote ); 
$id        =~ tr|+/=|-_.|; # Make non-word characters URL-friendly

or what Apache::Session uses:

Code

use MD5; 
 
sub generate_id { 
    return substr(MD5->hexhash(time(). {}. rand(). $$. 'blah'), 0, 16); 
}

References:

[url=http://perlmonks.org/index.pl?node_id=10102]Re: Simple Session?
[url=http://perlmonks.org/index.pl?node_id=36996](Ovid) Re: sessions: MD5 versus random strings

Please note that this question belonged in the Beginners forum -- it is not an Advanced question.

(This post was edited by Jasmine on Jan 1, 2003, 10:31 AM)

Paul
Enthusiast

Jan 2, 2003, 4:04 AM

Post #3 of 5 (2557 views)

Re: [webhay] return value from function [In reply to]	Can't Post

If you are going to generate a random string, make it easy for yourself a least :)

Code

sub my_rand { 
   my @rand = ('A'..'Z','a'..'z',0..9); 
   my $high = 32; 
   my $rand; 
   $rand .= $rand[rand @rand] for (0..$high); 
   return $rand; 
}

(This post was edited by Paul on Jan 2, 2003, 4:05 AM)

webhay
Novice

Jan 2, 2003, 10:58 AM

Post #4 of 5 (2552 views)

Re: [Jasmine] return value from function [In reply to]	Can't Post

thanks your script very cute and effective

webhay

In Reply To

uri
Thaumaturge

Jan 19, 2003, 9:18 PM

Post #5 of 5 (2488 views)

Re: [Jasmine] return value from function [In reply to]	Can't Post

In Reply To

To answer your question....

Code

sub gensid {  
    my $sid = ''; 
    my @alpha= qw/ q w e r t y u i o p l k j h g f d s 
                   a m n b v c x z 6 7 8 9 0 5 4 3 2 1 / ; 
 
    $sid .= $alpha[ int rand @alpha ] for 1 .. 32; 
    return $sid; 
}

Please note that this question belonged in the Beginners forum -- it is not an Advanced question.

well, let's fix that problem by adding some advanced comments Smile

since @alpha is declared and initialized inside the sub but it is readonly, it can be moved to before the sub itself. then it will get initialized only once at load time.

but that means that other subs could either access @alpha or have a name collision with it. so you just wrap both @alpha and the sub in one block:

Code

my @alpha= qw/ q w e r t y u i o p l k j h g f d s 
                   a m n b v c x z 6 7 8 9 0 5 4 3 2 1 / ; 
 
sub gensid {  
    my $sid = ''; 
  
    $sid .= $alpha[rand @alpha ] for 1 .. 32; 
    return $sid; 
}

notice that we also dropped the int as array indexing already provides an integer context.

finally we can be cute and reduce the code to one line:

Code

   return join '', map $alpha[rand @alpha], 1 .. 32;

let perl do more of the work for you. Cool

uri

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