Code that rot13s the output when it is rot13'd [closed]

Question

In case the title was confusing, I mean something like the following C code:

main(){}znva(){}

When rot13 encoded, the code becomes

znva(){}main(){}

and still runs.

But that isn't a valid answer, because of these rules:

• Your code must produce output. Code that doesn't produce output is disqualified.
• The program can't be empty. That's disqualified too.
• The program can't be the same or similar to the output. This means that you can't use Golfscript or PHP.

In a valid answer, the program produces some output without being rot13'd, such as:

Hello, World!

And when the program is rot13'd, the output changes to the following:

Uryyb, Jbeyq!

which is the rot13 of Hello, World!.

Have fun!

Answer 1

Ruby

Cheaty answer:

$><<'Hello, world!'

Slightly less cheaty answer:

s='Hello, world!'
$-I?puts(s):chgf(s)

Golf (15 chars)

$-I?p(:a):c(:a)

Answer 2

Perl, 25 14 12 characters

I believe this adheres to all of the requirements:

$_=a;fnl;say

Outputs a. After rot13 the program looks like this:

$_=n;say;fnl

and outputs n.

Answer 3

Brainf**k

Since you never said the output had to actually be affected by rot13, this is totally a valid answer:

-.

Not sure why it was downvoted, although it is kind of a cheap answer.

Answer 4

PHP 6

H<?//a

The program and its output differ by 83%, so not similar.
a is not transformed into output, should satisfy all rules now.

Answer 5

bash, 64 chars

_() { [[ "${1:0:1}" > U ]]&&rpub $@||echo $@; };_ Hello, Jbeyq.