Re: Common hash keys

use strict;
use vars qw($hashRef1 $hashRef2);
#code that puts values into the hashes

my @keyIntersection =
  grep exists($hashRef2->{$_}), keys %$hashRef1;

# Or if you just want to know if there are any

use List::Util;
my $hasInt =
   first {exists $hashRef2->{$_}} keys %$hashRef1;
[download]

$hasInt will be undef unless there's an intersection.
But be careful, it will be 0 if the first interecting key is '0'

throop

Comment on Re: Common hash keys Download Code

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Re^2: Common hash keys by lodin (Hermit) on Jun 08, 2008 at 06:37 UTC
There's no need to be careful if you handle the 0 case directly: `use List::Util; my $hasInt = defined first { exists $hashRef2->{$_} } keys %$hashRef1 ;` [download] lodin	[reply] [d/l]
Re^3: Common hash keys by BrowserUk (Patriarch) on Jun 08, 2008 at 07:11 UTC
Actually, there's no need to be careful or test for definedness. List::Util`::first()` returns the result of the code block, in this case the boolean return of the exists function. The values associated with the keys never come into it. `use List::Util qw[ first ];; my $a = { a=>0, b=>0, c=>0 }; my $b = { c=>0, d=>0, e=>0 }; if( first{ exists $b->{ $_ } } keys %$a ) { print "Common keys!"; } Common keys!` [download] Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error. "Science is about questioning the status quo. Questioning authority". In the absence of evidence, opinion is indistinguishable from prejudice. "Too many [] have been sedated by an oppressive environment of political correctness and risk aversion."	[reply] [d/l] [select]
Re^4: Common hash keys by tinita (Parson) on Jun 08, 2008 at 12:11 UTC
List::Util::first() returns the result of the code block, in this case the boolean return of the exists function. i think it returns the key it's iterating over, just like grep works. from the docs: "first returns the first element where the result from BLOCK is a true value." `use List::Util qw[ first ]; my $a = { 0 => 0 }; my $b = { 0 => 0 }; if( first{ exists $b->{ $_ } } keys %$a ) { print "Common keys!"; }` [download] prints nothing.	[reply] [d/l]
Re^5: Common hash keys by BrowserUk (Patriarch) on Jun 08, 2008 at 15:51 UTC
Re^2: Common hash keys by Anonymous Monk on Jun 07, 2008 at 18:55 UTC
That's the one. Thank you. `use List::Util 'first'; if(first{exists $hashRef2->{$_}} keys %$hashRef1 ) # }` [download]	[reply] [d/l]


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