why the value of count will be change?

[yueli711]

Hello, Below is the program to calculate average value. I really do not understand why the value of "count" will change. Thanks in advance!

use strict;
use warnings;

sub total {
my $sum;
foreach (@_){
$sum += $_;
}
$sum;
}




sub average {
if (@_==0){return}
my $count=@_;
my $sum =total(@_);
$sum/$count;
}