G'day smartyollie,

There's a semantic issue here. Hashes consist of zero or more pairs of keys and values: talking about a "null hash value" probably isn't what you meant.

I suspect, from the code you've posted, you meant a hash without any key/value pairs. If so, keys will probably do what you want. Here's an example:

#!/usr/bin/env perl -l

use strict;
use warnings;

my %multi = (empty => {}, data => { a => 1 });

for my $key (keys %multi) {
    if (keys %{$multi{$key}}) { 
        print "Data found in $key";
    }
    else {
        print "Data not found in $key";
    }
}
[download]

Output:

$ pm_1129100_complex_hash_check.pl
Data found in data
Data not found in empty
[download]

If I haven't guessed correctly, please read "Checking Variable for Not Null". This was posted last week and contains a discussion about NULL not being a Perl concept, per se. Having done that, please reword your question, replacing "null" with undefined, zero-length, FALSE or whatever you feel is most appropriate.

What I have is a key/value pair, where the value is a zero-length value. I was referring to that as "null".

Then you'll want the length() function which can be found in "Perl functions A-Z".

-- Ken

So it looks like the hash %hh has a key of 'QUESTION_TEST', who's value is itself another hash, so $value will always be a reference to that hash.

I think you need to post more code above this section, particularly where %hh hash is being defined and set up. You also need to explain what CHECKSOMETHING actually is.

-stevieb

I've tried various things for CHECKSOMETHING, see the four IF statements I listed at the end of my post.

ahhh, I see. Again though, it does appear from what you've posted that $value DOES contain data, and if that's the case, all of your tests will be true.

One way to see if I'm correct in thinking you've got a defined value (hashref) is this:

print "it's a hashref\n" if ref($hh{'QUESTION_TEXT'}) eq 'HASH';
[download]

-stevieb

you can try the next code as its worked for me:

my %hh = ('QUESTION_TEXT' => 0);
# my %hh = ('QUESTION_TEXT' => {});
# my %hh = ('QUESTION_TEXT' => {'F'=> 3});


my $value = $hh{'QUESTION_TEXT'};


if(ref($value) eq 'HASH'){
    $HashSize = @TemArr = keys $hh{'QUESTION_TEXT'};    # to get hash 
+size to tesitng
}else{
    $HashSize = 1;    # not hash (may be ARRAY or SCALAR or ... etc)
}
# print "--[$HashSize]\n"; 

if($HashSize){
    print "[$value]\n";
}else{
    print "[NULL]\n";
}
[download]

Thank you, this works although it gives me a perl warning
keys on reference is experimental at <program>.pl line NNN.
How to suppress?

keys %{ $hh{'QUESTION_TEXT'} } or better yet, IMHO,  keys %$value (untested).

---

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