pinnacle has asked for the wisdom of the Perl Monks concerning the following question:

package

package Average; # D e c l a r e  a  p a c k a g e
                # A v e r a ge  a  l i s t  o f  g r a d e s

sub av {
$total = 0;
@grades = (3,4,5);

$num_of_grades =$#grades + 1;
foreach $grade ( @grades ) {
     $total += $grade;
}
 $res = $total/$num_of_grades;   #  W h a t  g e t s  r e t u r n e d
#print $res;
return;
}
#&av;

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My perl script which calls above package



#!/usr/bin/perl

use warnings;
use Average;

$d = Average::av($res);
print $d;

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When I run my script it gives me an error as stated below, I am missing some basic thing, please assist


Name "main::res" used only once: possible typo at ./ave.pl line 6.
Use of uninitialized value $d in print at ./ave.pl line 7.

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Replies are listed 'Best First'.
Re: Finding average using package subroutine
by toolic (Bishop) on Jul 14, 2011 at 00:09 UTC
    If you make the following changes, it should print "4": 
    package Average; # D e c l a r e  a  p a c k a g e
                # A v e r a ge  a  l i s t  o f  g r a d e s
sub av {
$total = 0;
@grades = (3,4,5);

$num_of_grades =$#grades + 1;
foreach $grade ( @grades ) {
     $total += $grade;
}
 $res = $total/$num_of_grades;   #  W h a t  g e t s  r e t u r n e d
#print $res;
return $res;
}

1;
#&av;

    [download]

    ...and your script... 

    use warnings;
use Average;

$res = Average::av();
print $res;

    [download]

    You really meant to return a value ($res) from your sub. Eventually, you will probably also want to pass something as an argument to your sub. See also:

[reply]
[d/l]
[select]
      I'm sort of teaching myself perl and have a similar problem. I used the problem above but I'm not getting the same results. I want to find the average using a <STDIN> and subroutines.

      here's what I've got:

      sub:

      sub avg {
      $n = 0;
      @array = (<STDIN>);


      $total =$#array + 1;

      foreach $array ( @array ) {
      $n += $array;
      }
      $res = $n/$total;
      return $res;
      }

      1;

      function:
      #!/usr/bin/perl

      require 'obj13-lib.pl';

      $res = avg();
      print $res;

      Where am I going wrong?
[reply]
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