in reply to Re: how do I sort on two fields in a hash table?
in thread how do I sort on two fields in a hash table?

I believe your or binds too loosely so you get: 
( sort {$b->{'count'} cmp $a->{'count'} ) or
        $b->{'type'} cmp $a->{'type'}} @data

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(Note the parentheses above indicating the binding).

What you want is: 

sort {$b->{'count'} <=> $a->{'count'} ||
      $b->{'type'} cmp $a->{'type'}} @data

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Which binds more tightly. I also flipped the comparison operator for count since as dvergin pointed out above you probably want a numeric comparison for count.

-ben

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Re: Re: Re: how do I sort on two fields in a hash table?
by lhoward (Vicar) on Mar 16, 2001 at 01:43 UTC
    I don't think so... my test program: 
    #!/usr/bin/perl -w
use strict;
my @a;
push @a,{x=>1,y=>1};
push @a,{x=>2,y=>1};
push @a,{x=>1,y=>2};
push @a,{x=>2,y=>3};
push @a,{x=>2,y=>2};
foreach(sort {$a->{x} <=> $b->{x} or $a->{y} <=> $b->{y}} @a){
  print " $_->{x}  $_->{y}\n";
}

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    prints the correct results: 
    $ ./sort.pl 
 1  1
 1  2
 2  1
 2  2
 2  3

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Re: Re: Re: how do I sort on two fields in a hash table?
by vonman (Acolyte) on Mar 16, 2001 at 00:50 UTC
    Thanks for your response. I thought that || was the same as or. How are they different? Txs
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      They do the same thing, it's all about operator precedence. || has higher precedence than or, and other things in between. The perlop manpage has about everything you need to know. To steal an example from perlop, the following:
          unlink "alpha", "beta", "gamma" or gripe(), next LINE;
      works like:
          unlink("alpha", "beta", "gamma") or (gripe(), next LINE);
      but it would break using ||, because it would work like:
          unlink("alpha", "beta", ("gamma" || gripe()), next LINE;

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