You can't actually put anything except scalars into a hash or an array, so you have to put a reference to the array into the hash.

@b_griph = ('foo', 'bar');

%griph=('c' => \@c_griph,
        'b' => \@b_griph,
        'f' => \@f_griph,
        'o' => \@o_griph,
        'r' => \@r_griph,
        'm' => \@m_griph,
        'y' => \@y_griph,
        'g' => \@g_griph,
        'p' => \@p_griph,
        'w' => \@w_griph);

print "c = ",@{$griph{'c'}},"\n";
print "b = ",@{$griph{'b'}},"\n";
print "f = ",@{$griph{'f'}},"\n";
print "o = ",@{$griph{'o'}},"\n";
print "r = ",@{$griph{'r'}},"\n";
print "m = ",@{$griph{'m'}},"\n";
print "y = ",@{$griph{'y'}},"\n";
print "g = ",@{$griph{'g'}},"\n";
print "p = ",@{$griph{'p'}},"\n";
print "w = ",@{$griph{'w'}},"\n";

__END__
output
======
c =
b = foobar
f =
o =
r =
m =
y =
g =
p =
w =
[download]

by the way, the print code can be simplified to:

foreach $key (keys(%griph)) {
   print("$key = @{$griph{$key}}\n");
}
[download]

Data::Dumper is very useful for debugging:

use Data::Dumper;
print(Dumper(\%griph));
[download]

You have to reference the arrays first:

%griph=('c' => \@c_griph,
        'b' => \@b_griph,
        'f' => \@f_griph,
        'o' => \@o_griph,
        'r' => \@r_griph,
        'm' => \@m_griph,
        'y' => \@y_griph,
        'g' => \@g_griph,
        'p' => \@p_griph,
        'w' => \@w_griph);
[download]

use Data::Dumper;

my @array = 1 ..5;
my %hash = (a => @array, b => 'foo');

print Dumper \%hash;
[download]

So, now that you have referenced the arrays, you have to de-reference them in order to use them, like so:

print "$_\n" for @{ $griph{c} };
[download]

L-LL-L--L-LL-L--L-LL-L--
-R--R-RR-R--R-RR-R--R-RR
B--B--B--B--B--B--B--B--
H---H---H---H---H---H---
(the triplet paradiddle with high-hat)

If the array @c_cgraph is empty, then that part of the list is equivalent to:  %griph = ( c, (), b, (), ...

which is equivalent to  %griph = ( c, b, ...

hence your results.

You almost certainly want

%griph=('c' => \@c_griph,
        'b' => \@b_griph,
...
[download]

You want array ref, not array as hash values.

Also use Data::Dumper, so you don't need to code to dump the hash.

Now I get it! Thanks guys!

... and since you are using *array references* instead of arrays, you dont really need @c_griph, @b_griph, (and the rest) to begin with. You can save yourself a lot of keystrokes, potential bugs, (and hassle if you later need to add @z_griph, @zzz_griph and so forth) if you just use ...

@griph_keys         = qw( c b f o r m y g p w);
@griph{@griph_keys} = ();
$griph{f}           = ['foo','faa'];
$griph{c}           = ['coo','caa'];
$griph{b}           = ['bee','baa'];
$griph{r}           = ['ree','raa'];

use Data::Dumper;
print(Dumper(\%griph));
[download]

... hope that make sense.