Question

I have an array of hash references:

my @price = (
    {
        id    => '1',
        label => 5.00
    },
    {
        id    => '2',
        label => 7.50
    },
);

I also have 2 variable integers, $diff and $last. when I try to iterate over the array to multiply the “label” by $diff/$last:

foreach (@price) {
    print "(($diff/$last)*$_->{label})\t";
}

i get the following output:

((12/30)*5.00)
((12/30)*7.50)

I assume it is not multiplying because I have two integers and a hash reference. If this is correct, how can I make the hash reference an integer? How can I force Perl to actually do the math and print the resulting product?

Answer 1

It’s not multiplying because all of that is inside the double quotes. You need to do:

print( (($diff/$last)*$_->{label}) . "\t" );

The way you’re doing it perl is simply interpolating the variables and printing their values because they are enclosed within the quotes. The * is simply treated as a character to print. The above does the math then the . causes a concatenation to "\t" (which converts the result to a string).

$a = 5;
$b = 6;
print "$a + $b\n";
print $a + $b . "\n";

Outputs:

5 + 6
11