#!/usr/bin/perl

use warnings;
my (%a, %b, $c);
my $x = "$a{'foo'} $b{'bar'} $c"

##</code><code>##

Use of uninitialized value $a{"foo"} in concatenation (.) or string at main.pl line 5.
Use of uninitialized value in concatenation (.) or string at main.pl line 5.
Use of uninitialized value $c in concatenation (.) or string at main.pl line 5.