Re: Sorting hash keys according to different criteria

[George_Sherston]

Depending on what you're doing with this you might find an array of hashes useful. This would give you the data in the fixed order ordained by the calendar - you could then pull it out however you liked, and even have a framework for adding more info.

my @months = (
    {
        name => "January",
        days => 31,
    },
    {
        name => "February",
        days => 28,   # or whatever... there's another prob
    },

etc etc etc

You could then use the month number returned by localtime to pull data out of this array.

Having said that, if you're doing a lot of date calculations, then half an hour rummaging around in CPAN would probably save you time.

§ George Sherston

[Anonymous Monk]

Hi, Can I ask why this only prints one item in the hash array?

my %people;
%people =(
          {
            name => "fred",
            age  => 31,
          },
          {
            name => "bill",
            age  => 32,
          });

my $length = keys %people ;
print "$length\n";

foreach my $key (sort keys %people)
{
 print("$people{$key}{'name'}: $people{$key}{'age'}\n");
}

Code tags - dvergin 2003-06-24

[George_Sherston]

It's because you've mixed up a hash of hashes with an array of hashes. %people is clearly a hash; but the thing after the = is an array of two hashes. But since, in Perl, hashes are a special kind of array, Perl just took you at your word that you wanted to treat this array as a hash.

The end result is, %people is a hash with one key-value pair: the key is { name => "fred", age => 31, } and the value is { name => "bill", age => 32, }! I know that's not what you wanted, but it's what you told Perl to do!

You'd get the output you want with

my @people = (
    {
        name => "fred",
        age => 31,
    },
    {
        name => "bill",
        age => 32,
    }
);

for (@people) {
    print "$_->{'name'}: $_->{'age'}\n";
}

By the way, to make your posts easier to read, you can enclose your code with <code> tags!

§ George Sherston