perl hash printing the value of a key

Question

the below script stores the key value pairs. Based on the input key given it should retrieve the corresponding value. In below code I am able to see the key value pairs from the first print but when I give one of the keys as an input, it throws an error saying "uninitialized hash". How to solve this ?

...
for my $key ( sort keys %hash ) {
    print "$key = $hash{$key}\n"; 
}
 my $key = <STDIN>;
 print "list is = $hash{$key}\n";

Answer 1

$key contains the line entered including the trailing line feed . Add

chomp($key);