Re: how can i return the common keys from a hash

If u want to return the common keys from hashes,use the fallowing sub to pass hash ref as arguments to sub.

@repeat=common(\%a,\%b,\%c);
sub common
{
  my %d;
 for my $href(@_)
  {
    while(my $m=each %$href)
     $d{$m}++;
   }
}
 return grep {$d{$_} ==@_} keys %d
}
[download]

Comment on Re: how can i return the common keys from a hash Download Code

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Re^2: how can i return the common keys from a hash by ivancho (Hermit) on Aug 05, 2006 at 01:19 UTC
I am somewhat puzzled by the following DWIM: in scalar context, `each` returns the next key of the hash. Why doesn't, then, the assignment `"my $m = each %$href"` return false if the key is "0"? ie `> perl -wle 'my %a = ( 0 => 1, y => 2, z => 4); while (my $m = each %a +) { print $m }' y 0 z > perl -wle 'my @a = ( 0 => 1, y => 2, z => 4); while (my $m = pop @a) + { print $m }' 4 z 2 y 1 > perl -wle 'my @a = ( 0 => 1, y => 2, z => 4); while (my $m = shift @ +a) { print $m }' >` [download]	[reply] [d/l] [select]
Re^3: how can i return the common keys from a hash by imp (Priest) on Aug 05, 2006 at 01:42 UTC
`perl -MO=Deparse -wle 'my %a = ( 0 => 1, y => 2, z => 4); while (my $m + = each %a) { print $m }' BEGIN { $^W = 1; } BEGIN { $/ = "\n"; $\ = "\n"; } my(%a) = (0, 1, 'y', 2, 'z', 4); while (defined(my $m = each %a)) { print $m; }` [download] It checks for defined as the loop condition, not a true value.	[reply] [d/l]
Re^4: how can i return the common keys from a hash by ivancho (Hermit) on Aug 05, 2006 at 02:07 UTC
indeed, as that's what you want in 99% of the cases.. I was mostly pointing out that it's neither logical, nor obvious from docs	[reply]