No values being output - perl

Question

I'm having a problem coding my first Perl program.
What I'm trying to do here is getting the maximum, minimum,total and average of a list of numbers using a subroutine for each value and another subroutine to print the final values. I'm using a "private" for all my variables, but I still couldn't print my values.
Here is my code:
&max(<>);
&print_stat(<>);
sub max {
my ($mymax) = shift #_;
foreach (#_) {
if ( $_ > $mymax ) {
$mymax = $_;
}
}
return $mymax;
}
sub print_stat {
print max($mymax);
}

Answer 1

Please try this one:
use strict;
use warnings;
my #list_nums = qw(10 21 30 42 50 63 70);
ma_xi(#list_nums);
sub ma_xi
{
my #list_ele = #_;
my $set_val_max = '0'; my $set_val_min = '0';
my $add_all_vals = '0';
foreach my $each_ele(#list_ele)
{
$set_val_max = $each_ele if($set_val_max < $each_ele);
$set_val_min = $each_ele if($set_val_min eq '0');
$set_val_min = $each_ele if($set_val_min > $each_ele);
$add_all_vals += $each_ele;
}
my $set_val_avg = $add_all_vals / scalar(#list_ele) + 1;
print "MAX: $set_val_max\n";
print "MIN: $set_val_min\n";
print "TOT: $add_all_vals\n";
print "AVG: $set_val_avg\n";
#Return these values into array and get into the new sub routine's
}

Answer 2

Some notes
Use plenty of whitespace to lay out your code. I have tidied the Perl code in your question so that I could read it more easily, without changing its semantics
You must always use strict and use warnings 'all' at the top of every Perl program you write
Never use an ampersand & in a subroutine call. That hasn't been necessary or desirable since Perl 4 over twenty-five years ago. Any tutorial that tells you otherwise is wrong
Using <> in a list context (such as the parameters to a subroutine call) will read all of the file and exhaust the file handle. Thereafter, any calls to <> will return undef
You should use chomp to remove the newline from each line of input
You declare $mymax within the scope of the max subroutine, but then try to print it in print_stat where it doesn't exists. use strict and use warnings 'all' would have caught that error for you
Your max subroutine returns the maximum value that it calculated, but you never use that return value
Below is a fixed version of your code.
Note that I've read the whole file into array #values and then chomped them all at once. In general it's best to read and process input one line at a time, which would be quite possible here but I wanted to say as close to your original code as possible
I've also saved the return value from max in variable $max, and then passed that to print_stat. It doesn't make sense to try to read the file again and pass all of those values to print_stat, as your code does
I hope this helps
use strict;
use warnings 'all';
my #values = <>;
chomp #values;
my $max = max(#values);
print_stat( $max );
sub max {
my $mymax = shift;
for ( #_ ) {
if ( $_ > $mymax ) {
$mymax = $_;
}
}
return $mymax;
}
sub print_stat {
my ($val) = #_;
print $val, "\n";
}
Update
Here's a version that calculates all of the statistics that you mentioned. I don't think subroutines are a help in this case as the solution is short and no code is reusable
Note that I've added the data at the end of the program file, after __DATA__, which lets me read it from the DATA file handle. This is often handy for testing
use strict;
use warnings 'all';
my ($n, $max, $min, $tot);
while ( <DATA> ) {
next unless /\S/; # Skip blank lines
chomp;
if ( not defined $n ) {
$max = $min = $tot = $_;
}
else {
$max = $_ if $max < $_;
$min = $_ if $min > $_;
$tot += $_;
}
++$n;
}
my $avg = $tot / $n;
printf "\$n = %d\n", $n;
printf "\$max = %d\n", $max;
printf "\$min = %d\n", $min;
printf "\$tot = %d\n", $tot;
printf "\$avg = %.2f\n", $avg;
__DATA__
7
6
1
5
1
3
8
7
output
$n = 8
$max = 8
$min = 1
$tot = 38
$avg = 4.75