grep is one way:

use warnings;
use strict;

my $input_val = 'abc';
my @names = ("abc", "def", "ijk");

if (grep { $input_val eq $_ } @names)
{print "Match Found";}
else
{ print "Match Failed";}

print "\n";
[download]

See also (for potentially faster look-ups):

• Hashes
• List::Util