You can use map on the expanded hash to alter any undef'ined value to be equal to '' instead. As you cannot use undef as a hash key (it is turned into a string, so becomes '' (although a literal 'undef' becomes the string 'undef')) then this won't hurt any of the keys:

%new_hash = map {defined($_) ? $_ : ''} %{$ref2};

For your example you could replace all the code above with something along the lines of:

$rh_foo = {a=>undef, b=>'b_value', c=>undef, e=>'e_value'};

push @foo, { map {defined($_) ? $_ : ''} %{$rh_foo} };

foreach (keys %{$foo[0]}) {
  print "$_ => ${$foo[0]}{$_}\n";
}

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In reply to Re: setting values in anonymous hash by quidity
in thread setting values in anonymous hash by agoth

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