Hi,

I wanted to test if there are any data in a hash. So, I was thinking of simply using something like this... 
#!/usr/bin/perl

my %a = ( 'a' => '111' );
%a = ();

print "test_1" if ( %a );
print "test_2" if ( defined( %a ) );

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If I run this, 'test_1' is not printed which means there are no data in the hash. This is what I want.

But for some reason, 'test_2' is printed. Since I initialized the hash, shouldn't it be undefined already? I'm just curious why it printed. I checked the documentation and it did mention that using something like defined( %hash ) is already deprecated and I should just use ( %hash ) to test for the presence of the data in the hash.

Now, if I try to make a small change to this code where I declare and initialize the hash at the same time... 
use strict;

my %a = ();  ## This is the change.

print "test_1" if ( %a );
print "test_2" if ( defined( %a ) );

[download]
Then, nothing will be printed at all. Didn't I initialized the hash in both cases?

Any ideas on this?

In reply to Test Presence of Data in Hash by bichonfrise74

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