Re: Common hash keys

If you want to know which keys they have in common:

  DB<1> %a = (a => 1, b =>2, c => 3); %b = (b =>2, c => 1, d => 4)
  DB<2> $seen{$_}++ for (keys(%a), keys(%b))
  DB<3> x grep { $seen{$_} > 1 } keys(%seen)
0  'c'
1  'b'
[download]

If the only thing you want is to know if they have some key in common:

  DB<1> use List::Util qw{first}
  DB<2> %a = (a => 1, b =>2, c => 3); %b = (b =>2, c => 1, d => 4)
  DB<3> x first { ++$seen{$_} > 1 } (keys(%a), keys(%b))
0  'c'
[download]

Hope it helps

Comment on Re: Common hash keys Select or Download Code

Replies are listed 'Best First'.
Re^2: Common hash keys by FunkyMonk (Chancellor) on Jun 07, 2008 at 10:41 UTC
`DB<2> $seen{$_}++ for (keys(%a), keys(%b)) DB<3> x grep { $seen{$_} > 1 } keys(%seen)` [download] 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;` [download] 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;`~~ ~~[download]~~ Unless I state otherwise, all my code runs with strict and warnings	[reply] [d/l] [select]
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` [download] Here you should just stick with `my`. lodin	[reply] [d/l] [select]