in reply to [Homework Question] Subroutines & References

sub above_mean {
     $i == mean(@list_of_numbers); 
    foreach (@list_of_numbers) {
         if ($a > $i) {  
             print "$a is above mean, which is mean(@list_of_numbers)"
+;
         }
#........^ this is missing
    }
#...^ so is this
}

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Re^2: [Homework Question] Subroutines & References
by Hayest (Acolyte) on Feb 11, 2015 at 16:28 UTC 
    #!/usr/bin/perl
use warnings;
use List::Util qw(sum);

my @list_of_numbers = (1 .. 50);
my $i = ();
my $a = ();

sub mean {
    return sum(@_)/@_;
}

sub above_mean {
    $i == mean(@list_of_numbers);
    foreach (@list_of_numbers) {
        if ($a > $i) {
            print "$a is above mean, which is mean(@list_of_numbers)";
        }
    }
}

print above_mean(@list_of_numbers);

    [download]

    This now returns: 

    Use of uninitialized value $a in numeric gt (>) at main.pl line 16.

    [download]

    However, I thought I declared $a earlier in my program?

[reply]
[d/l]
[select]
      == is the numeric comparison operator, not the assignment operator, which is quite similar: =. See perlop for details. warnings should have told you: 
      Useless use of numeric eq (==) in void context at ...

      [download]

      Also, you don't populate $a anywhere. Maybe, you meant 

      foreach my $a (@list_of_numbers) {

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      لսႽ† ᥲᥒ⚪⟊Ⴙᘓᖇ Ꮅᘓᖇ⎱ Ⴙᥲ𝇋ƙᘓᖇ
[reply]
[d/l]
[select]
        I realized the == error once it executed, however, you helped out with the suggestion of the foreach statement. I've got it running properly now. Thank you!
[reply]
      print above_mean(@list_of_numbers);

      Just as a matter of curiosity, you might try this variation on the quoted statement:
          print above_mean();
      Does calling the  above_mean() function without any parameters make any difference to the value returned by the function? If not, why not?

      Give a man a fish:  <%-(-(-(-<

[reply]
[d/l]
[select]
        calling above_mean(); function without parameters make does not make any difference to the value returned by the function. I believe this is because @numbers (which I had as the parameter) is already declared inside of my subroutine above_mean - is this accurate?
[reply]
[d/l]

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