>perl -wMstrict -MData::Dumper -le
"my @array = qw(A B C);
 $_ = 'foo';
 print qq{before foreach loop:};
 print Dumper $_, \@array;
 foreach (@array) {
   print qq{in foreach loop before while loop: \$_ is $_};
   { local $_;  while (<DATA>) { print; } }
   print qq{in foreach loop after while loop:  \$_ is },
         defined() ? $_ : 'UNdefined'
         ;
   }
 print qq{after foreach loop:};
 print Dumper $_, \@array;
 __DATA__
"
before foreach loop:
$VAR1 = 'foo';
$VAR2 = [
          'A',
          'B',
          'C'
        ];

in foreach loop before while loop: $_ is A
in foreach loop after while loop:  $_ is A
in foreach loop before while loop: $_ is B
in foreach loop after while loop:  $_ is B
in foreach loop before while loop: $_ is C
in foreach loop after while loop:  $_ is C
after foreach loop:
$VAR1 = 'foo';
$VAR2 = [
          'A',
          'B',
          'C'
        ];