my %hash = ('a'=>1, 'b'=>1, 'c'=>1);
@hash{'a'..'c'} = 2;

##</code><code>##

$VAR1 = {
          'a' => 2,
          'b' => undef,
          'c' => undef
        };

##</code><code>##

my %hash = ('a'=>1, 'b'=>1, 'c'=>1);
@hash{'a'..'c'} = 2;
use Data::Dumper;
print Dumper  \%hash;

%hash = ('a'=>1, 'b'=>1, 'c'=>1);
($hash{'a'}, $hash{'b'}, $hash{'c'}) = 2;
print Dumper  \%hash;