Re^5: setting PERL_PERTURB_KEYS & PERL_HASH

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]

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

Comment on Re^5: setting PERL_PERTURB_KEYS & PERL_HASH_SEED in a perl file Select or Download Code

Replies are listed 'Best First'.
Re^6: setting PERL_PERTURB_KEYS & PERL_HASH_SEED in a perl file (sort) by tye (Sage) on Jul 18, 2016 at 13:20 UTC
`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	[reply] [d/l]
Re^6: setting PERL_PERTURB_KEYS & PERL_HASH_SEED in a perl file by haukex (Archbishop) on Jul 18, 2016 at 13:21 UTC
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	[reply] [d/l] [select]
Re^7: setting PERL_PERTURB_KEYS & PERL_HASH_SEED in a perl file by gravid (Novice) on Jul 18, 2016 at 13:31 UTC
Thx Hauke! This is the solution. Works for me great :) Thx Guy	[reply]