Re: Sorting a hash

On Mon, Jun 2, 2008 at 1:53 PM, Iain Adams <[email protected]> wrote:

> Hello,
>
> I am trying to sort a hash of hashes.
>
> my code looks like this
>
>  foreach $cnt (sort keys %{ $relations{ $uid }{ "instances" } }){
>             print OUT "$cnt 1, ";
>  }
>
> This prints out the correct numbers (the keys of the instances hash.
> However the sorting is a bit weird.  The keys are all integers yet
> when sorting the keys aren't put in number order. instead the first
> digit is seen as the qualifier.
>
> Here is an example output:
>
>  100 1, 120 1, 121 1, 122 1, 123 1, 124 1, 125 1, 126 1, 127 1, 132 1,
> 133 1, 134 1, 135 1, 136 1, 137 1, 138 1, 139 1, 221 1, 222 1, 223 1,
> 224 1, 225 1, 226 1, 227 1, 228 1, 235 1, 236 1, 237 1, 238 1, 239 1,
> 240 1, 241 1, 242 1, 323 1, 324 1, 325 1, 326 1, 327 1, 328 1, 329 1,
> 330 1, 50 1, 51 1, 52 1, 53 1, 54 1, 55 1, 56 1, 57 1, 93 1, 94 1, 95
> 1, 96 1, 97 1, 98 1, 99 1,
>
> As you can see it is not in normal order.
>
> Does anyone know why this is happening and how I can fix it?
>
> Thanks
>
>
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to numerically sort, you should use:

sort { $a <=> $b } keys %{ $relations{ $uid }{ "instances" }  }

when you omit { $a <=> $b }, perl is using default string comparison:
{ $a cmp $b}

Jialin