## Writing Safe Code

### An example program using *my* (I)

Let's look at a modified version of Example 3 from the Functions chapter, where we will calculate the average of the squares of a list of numbers. (We will see a more detailed example in the next slide)
#### Example

#!/usr/local/bin/perl
my @numbers = (2, 3, 4, 5);
my $ave2 = calc_ave_squares (@numbers);
print "Average: $ave2\n";
sub calc_ave_squares {
my (@list) = @_;
my ($no_of_elem, $result);
my $sum = 0;
$no_of_elem = scalar (@list);
foreach $i (@list) {
my $square = $i**2;
$sum += $square;
}
$result = $sum / $no_of_elem;
return $result;
}

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