I need to differentiate an empty array from an uninitialized one. Consider this example: 

# possible strings come in 4 versions 
   my $str_one =  "0,1,.5,0,1" ; 
   my $str_two =  ".5,,0,1," ;
   my $str_three = ",,,," ;
   my $str_four = "" ;

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Converting each $str to an array with

 my @array =  split ( "," , $_ )

yields a surprising result because the undefined elements are suppressed. So $str_one correctly gives @array = ( 0 1 .5 0 1) , but for $str_two the undefined element is skipped and the number of elements is 4 (instead of 5) . Even worse, with str_three and str_four the resulting array is empty (or may I say "undefined") in either case. By the way, the conversion is destructive, i.e. it's not possible to regain $str_three and $str_four by applying join ( "," , @array ). Is this a Perl 5 design flaw? Is there a proper way to work around this problem with Perl 5?

In reply to How to differentiate an empty array from an unitialized one? by iatros

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