You're close, but are missing what $a and $b are. They are not indexes, but
are the actual array references.
by_third_item {
return $a->[2] <=> $b->[2];
}
----- Original Message -----
From: "Charles Lu" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Sunday, February 24, 2002 12:27 PM
Subject: sorting with complicated data structure
> Hi all
>
> I am attempting to sort the following data. But I cannot get it to
work.
> Frankly i am not even sure I am allowed to do this in perl. Nonetheless
I
> hope anyone can give me some suggestions.
> Here is the data structure
>
> $query->{$reference}->[0] = ['a','b', 9, 12];
> $query->{$reference}->[1] = ['c','d', 4, 15];
> $query->{$reference}->[2] = ['e','f', 8, 30];
>
> so for example to print out the entire 1st array i would type
>
> print "@{ $query->{$reference}->[0] }";
>
> I want to sort the above 3 arrays by their 3rd element in ascending order.
> So the final correct order would be
>
> $query->{$reference}->[2] = ['a','b', 9, 12];
> $query->{$reference}->[0] = ['c','d', 4, 15];
> $query->{$reference}->[1] = ['e','f', 8, 30];
>
> #############################################
> HERE IS MY CODE (IT DOESN'T WORK)
> sub by_third_item {
>
> return $query->{$reference}->[$a][2] <=>
$query->{$reference}->[$b][2];
>
> }
>
> @sortedlist = sort by_third_item @{ $query->{$reference} };
> #############################################
>
> When run, the program "hangs" and i had to kill it. Can anyone suggest
what
> I am doing wrong? Thank you.
>
>
> charles
>
>
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