foreach my $invnumctr (sort { $inv{$a} <=> $inv{$b} } keys %inv) {
    print "$invnumctr is $inv{$invnumctr}\n";
}
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Jeff

R-R-R--R-R-R--R-R-R--R-R-R--R-R-R--
L-L--L-L--L-L--L-L--L-L--L-L--L-L--

(Apple=>10,
 Peach=>5,
 Berry=>9,
 Cobbler=>3,
 Cherry=>7
)
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(Apple, Peach, Berry, Cobbler, Cherry)
[download]

$inv{Apple} <=> $inv{Peach}    
$inv{Peach} <=> $inv{Berry}    
$inv{Peach} <=> $inv{Cobbler}   
...
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The important thing to remember is that it's still using just the keys to sort on!

Well actually it is sorting numerically on the values not the keys (PS I'm sure this was just a slip of the tongue and would have /msg if you'd been online). Anyway to clarify what boo_radley *meant*

%inv=(
    Apple   => 10,
    Peach   => 5,
    Berry   => 9,
    Cobbler => 3,
    Cherry  => 7
);

print "\nSort values numerically in ascending order\n";
foreach $key ( sort {$inv{$a} <=> $inv{$b}} keys %inv) { &print_it }

print "\nSort values numerically in descending order\n";
foreach $key ( sort {$inv{$b} <=> $inv{$a}} keys %inv) { &print_it }

print "\nSort keys alphabetically in alphabetical order\n";
foreach $key ( sort {$a cmp $b} keys %inv) { &print_it}
print "\nNote this is the same as\n";
foreach $key ( sort keys %inv) { &print_it}

print "\nSort keys alphabetically in reverse alphabetical order\n";
foreach $key ( sort {$b cmp $a} keys %inv) { &print_it }


sub print_it {
   print "$key\t=> $inv{$key}\n"
}
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You will see from the examples that we use <=> for numerical sorts and 'cmp' for alphabetical ones. We sort based on the arguments on each side of these operators. $a is one of the keys whereas $inv{$a} is the value in the $inv hash keyed by $a. You will also note that reversing the position of the arguments reverses the sort order. By default sort uses {$a cmp $b} which is an alphabetical sort in alphabetical order.

cheers

tachyon

s&&rsenoyhcatreve&&&s&n.+t&"$'$`$\"$\&"&ee&&y&srve&&d&&print

Let's say you have some hash:

my %h = (
    Foo => 73,
    Bar => 66,
    Rat => -1
);
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If you say sort keys %h you know will get the order Bar, Foo, Rat, which means when you look through the hash in that order you will find 66, 73, -1. You could also say sort { $a cmp $b } keys %h, but that would be a little redundant.

In essence, the sort routine is going to compare Foo with Bar, Bar with Rat and Rat with Foo to decide on the order.

If, however, instead of saying {$a cmp $b} we were to say {$h{$a} <=> $h{$b}}, we would be sorting on the value that Foo et al., point to. So we would be comparing 66 with 73, 66 with -1 and 73 with -1. We have to use the spaceship operator <=> because we are performing numerical comparisons.

If we were to foreach over the hash with the results of this sort, we would see Rat, Bar, Foo.

I hope that helps you understand how it works. It is a very useful trick to have around.

g r i n d e r

buckaduck