#!/usr/bin/perl

use strict;
use warnings;
               
my $x = do {for (1 .. 4) {}};
my @x = do {for (1 .. 4) {}};

printf "Scalar return value of for is %s\n",
               defined $x ? "defined" : "undefined";
printf "Scalar return value of for is %s\n",
               $x ? "true" : "false";
printf "Scalar return value of for is has length %d\n",
               length $x;
printf "Scalar return value of for is '%s'\n",
               $x;

printf "List return value of for returns %d element\n",
               scalar @x;
printf "List return value of for contains %d undefined elements\n",
               scalar grep {!defined} @x;
printf "List return value of for contains %d true elements\n",
               scalar grep {$_} @x;
printf "List return value of for contains %d elements of non-zero length\n",
               scalar grep {length} @x;
printf "List return value of for equals [%s]\n",
               join ", ", map {"'$_'"} @x;

__END__
Scalar return value of for is defined
Scalar return value of for is false
Scalar return value of for is has length 0
Scalar return value of for is ''
List return value of for returns 1 element
List return value of for contains 0 undefined elements
List return value of for contains 0 true elements
List return value of for contains 0 elements of non-zero length
List return value of for equals ['']