Re^2: Common hash keys


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Re^2: Common hash keys

by FunkyMonk (Chancellor)

on Jun 07, 2008 at 10:41 UTC ( [id://690825]=note: print w/replies, xml )

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in reply to Re: Common hash keys
in thread Common hash keys

DB<2> $seen{$_}++ for (keys(%a), keys(%b)) DB<3> x grep { $seen{$_} > 1 } keys(%seen)
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You can combine these two into a single statement:

use Data::Dump;

my %a = ( a => 1, b => 2, c => 3 );
my %b = ( b => 2, c => 1, d => 4 );

my %seen;
pp grep { $seen{$_}++ } keys %a, keys %b;
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Update: Don't use state variables for this. See lodin's reply

~~Or, with 5.10~~

pp grep { state %seen; $seen{$_}++ } keys %a, keys %b;
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Unless I state otherwise, all my code runs with strict and warnings

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Re^3: Common hash keys
by lodin (Hermit) on Jun 08, 2008 at 06:32 UTC

Be careful with that state. It won't do what (I think) you want.

use 5.010;
sub foo {
  my ($a, $b) = @_;
  sort grep { state %seen; $seen{$_}++ } keys %$a, keys %$b
}

my %a = ( a => 1, b => 2, c => 3 );
my %b = ( b => 2, c => 1, d => 4 );

say join ' ', foo(\%a, \%b);
say join ' ', foo(\%a, \%b);

__END__
b c
a b b c c d
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my

lodin

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