Hi Monks, 
use Data::Dumper;
$x = {};
1 if ( exists $x->{W} ) ;
1 if ( defined $x->{X} ) ;
1 if ( $x->{Y} ) ;
1 if ( exists $x->{Y}{X}  ) ;
1 if ( defined $x->{Z}{A}  );
print Dumper $x;

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Result :
$VAR1 = {
          'Z' => {},
          'Y' => {}
        };

[download]
What I don't want is Z, Y create by itself, when I try to check if some keys from inner are existed or not. Can I do that ? Hopefully this won't be the only solution 
if ( $x->{Y} ) {
  if ( $x->{Y}{Z} ) {
    1 if ( $x->{Y}{Z}{A} ) ;
  }
} ; # $VAR={};

[download]
Any clues? Thank you very much!

In reply to How do you check if a key exists without creating it ? by exilepanda

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