在Perl中将哈希中的所有值相乘？

Question

I would like to multiply all the values of a hash together without having to call the specific elements. Eg I DON'T want to do $hash{'kv1'} * $hash{'kv2'} * $hash{'kv3'} because I won't know the number of elements in the hash to do this.

I'm guessing there is a simple and efficient function to do this, maybe using each or something, but I can't find any examples to follow. Any ideas?

Answer 1

Start at 1 (since 1 multiplied by anything is what you multiple it by), then loop over the values of the hash and multiple the current total value by the value from the hash.

#!/usr/bin/env perl

use v5.12;
my %hash = ( a => 1, b => 2, c => 3, d => 4 );
my $value = 1;
$value = $value * $_ foreach values %hash;
say $value;

Answer 2

This is what List::Util 's reduce is for:

use List::Util 'reduce';

my %hash = (foo => 3, bar => 7, baz => 2);

say reduce { our $a * our $b } values %hash;

Output:

42

Answer 3

I would iterate over keys %hash like this:

my $prod = 1;
$prod *= $hash{$_} for keys %hash;

Answer 4

will this not do?

my $m = 1;
for (values %my_hash) {
    $m *= $_;
}