ref returns the type being referenced, or false if it is not a refernce (you see empty string when we try to use it as a string):

use strict;
use warnings;

my $a = 123;
my $aref = \$a;
my @b = (1,2,3);
my $bref = \@b;

print "[" . ref($a) . "]\n";
print "[" . ref($aref) . "]\n";
print "[" . ref($b) . "]\n";
print "[" . ref($bref) . "]\n";
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You can also use UNIVERSAL->isa():

use strict;
use warnings;

my $a = 123;
my $aref = \$a;
my @b = (1,2,3);
my $bref = \@b;

print UNIVERSAL::isa($aref, "SCALAR") + 0, "\n";
print UNIVERSAL::isa($bref, "ARRAY") + 0, "\n";
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