Your interpretation is correct, but to put it in actual Perl code, rather than pseudo-code, you could replace:

my $C = exists $opts{'c'} ? '!' : '';
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with, for example, this:

my $C;
if (exists $opts{'c'}) {
    $C = '!'; 
} else {
    $C = '';
}
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The semantic of the so-called ?: ternary operator (see: http://perldoc.perl.org/perlop.html#Conditional-Operator is essentially the following:

$c = condition ? value of $c if condition is true : value of $c otherw
+ise;
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