Hi gravid,

Could you show a short example of the kind of sort you're doing (some sample input data, brief code and expected output)? I'm almost certain there's a better solution than messing with Perl's internal hash settings and re-starting the interpreter.

Regards,
-- Hauke D

Hi,

Lets say we have this hash:

$hash{a} = 0;
$hash{b} = 1;
$hash{c} = 0;
$hash{d} = 3;
[download]

The expected output is:

a = 0
c = 0
b = 1
d = 3
[download]

or

c = 0
a = 0
b = 1
d = 3
[download]

(note how 'a' & 'c' are switched)

Both are correct!

However, for consistency, I rather have always the same output.

The code that I'm using is:

foreach my $k ( sort { $hash{$a} <=> $hash{$b}  } keys %hash  ) {
    print "$k = $hash{$k}\n";
}
[download]

Thx

Guy

sort { $hash{$a} <=> $hash{$b} || $a cmp $b }
[download]

I was sure that whatever written inside a BEGIN statement is hapannig before everything else, so I'm not sure why my first attempt did't wok

So you thought that the Perl code in a BEGIN block would be run by the perl interpreter before the perl interpreter was initialized? Surely it is not hard to see why that is not the case.

- tye        

Hi gravid,

Yep, there's a better solution than messing with Perl's internals :-)

my %hash = ( a=>0, b=>1, c=>0, d=>3 );
foreach my $k ( sort { $hash{$a} <=> $hash{$b} or $a cmp $b } keys %ha
+sh  ) {
    print "$k = $hash{$k}\n";
}
[download]

Always outputs:

a = 0
c = 0
b = 1
d = 3
[download]

Background: If the comparison of the values (<=>) shows they are equal it returns zero, so then the second part of the or expression is evaluated, comparing the keys.

Update: See the multi-field sort in How do I sort an array by (anything)? That FAQ answer also references this article: Far More Than Everything You've Ever Wanted to Know About Sorting

Hope this helps,
-- Hauke D