Implement ROT-47... in ROT-47

Question

Challenge: Implement ROT-47 in code that works as both itself and as the ROT-47 version of itself.

Scoring:

Your score is calculated as a percentage of used, ROT-47 eligible bytes in total of both versions of the program divided by total bytes (all characters) of both versions.

A used, ROT-47 eligible byte is any character that would be converted by the ROT-47 cipher that is not part of a comment or ignored by the compiler/interpreter. For example, any character in a brainfuck program that is not +-<>[],. is not considered a used byte, and any character in a C program including and after // or inside /* */ is not considered a used byte. All special symbols in APL are not considered used, as are all characters in a Whitespace program (sorry).

Ties will be broken by the program with the most upvotes. If there is still a tie, then the shortest program wins.

Example scoring:

C: 62/64 = 96.875%

Notice there is a space in this program. Obviously also, this program is not a valid entry because it doesn't even compile, but I wanted to show how scoring works.

main(){printf("Hello World!");}

Answer 1

Ruby, 100% (74 characters)

Input on STDIN, output on STDOUT.

Vj=s=gets;puts(s.tr'!-~','P-~!-O');Vj;'lDl86EDjAFEDWD]ECVP\OV[V!\OP\~VXj;'

The second line is the first line ROT-47'd. Therefore, when ROT-47ing the whole program, it becomes:

';lDl86EDjAFEDWD]ECVP\OV[V!\OP\~VXj';jV=s=gets;puts(s.tr'!-~','P-~!-O');jV

My strategy here is based upon the fact that:

• V is ' when ROT-47'd

• j is ; when ROT-47'd

• Therefore, Vj=...Vj; turns into ';l...';, which is essentially a no-op

  • Now you can create any arbitrary code that does anything normally and no-ops when ROT-47'd. This is because Vj=...Vj; can support running any code as you could do Vj=0;{INSERT ANY CODE};Vj;, and that will become '...'; when ROT-47'd. You just have to be careful not to use V in that code, since that will break it.

• Similar logic can be used in reverse to produce the second half (jV instead of Vj)

Answer 2

C - 54.6%

Y;BW;XL;jNj;AW(){XL^Y;};main(int i,char**v){char*x=v[1];while(*x){if(*x>32&&*x<128)*x=(*x+15)%94+32;putchar(*x++);}}//Y^Nj>2:?W:?E :[492CYYGXL492CYIlG,`.jH9:=6WYIXL:7WYImbaUUYIk`agXYIlWYIZ`dXThcZbajAFE492CWYIZZXjNN

When ROT-47-translated, we get

*jq(j){j;};jp(WXL){/*jNj>2:?W:?E :[492CYYGXL492CYIlG,`.jH9:=6WYIXL:7WYImbaUUYIk`agXYIlWYIZ`dXThcZbajAFE492CWYIZZXjNN^^*/};main(int i,char**v){char*x=v[1];while(*x){if(*x>32&&*x<128)*x=(*x+15)%94+32;putchar(*x++);}}

Both programs compile, and ROT-47-translate the first argument:

$ ./a "hello world"
96==@ H@C=5

Answer 3

GolfScript, 120 / 120 bytes = 100%

{:&&32>&&+254<*{7+7+94%33+}*}%LiUUbamUUZadckYLfZfZhcTbbZNYNT

or, in ROT-47:

LiUUbamUUZadckYLfZfZhcTbbZNYNT{:&&32>&&+254<*{7+7+94%33+}*}%

No comments or string abuse. The undefined command LiUUbamUUZadckYLfZfZhcTbbZNYNT (which equals the rest of the code in ROT-47) is a no-op, but it still gets executed by the interpreter, so I believe it counts as used.

This was actually a pretty easy challenge in GolfScript. The main difficulty was in avoiding the digit 1, which is mapped by ROT-47 into the GolfScript command `. The commands ., -, ,, \, [, /, ] and ^ also had to be avoided, but that was fairly easy in this case, since the task required no array building.

Bonus:

Here's a GolfScript period-2 quine (i.e. a program that prints a second program that prints the first program again) where the two programs are the ROT-47 transforms of each other:

{`'0$~'+.{7+7+94%33+}%@!{0$@@;}*}0$~L1V_SOVZ]LfZfZhcTbbZNToPL_SoojNYN_SO

This program outputs itself ROT-47 encoded, yielding another GolfScript program:

L1V_SOVZ]LfZfZhcTbbZNToPL_SoojNYN_SO{`'0$~'+.{7+7+94%33+}%@!{0$@@;}*}0$~

which, in turn, also outputs itself ROT-47 encoded, yielding the previous program again. Thus, this program is also a rotating quine.

Answer 4

python, 96.1% (?)

According to your definition, strings count as used code?

V=input();print("".join([chr(33+(ord(V[i])+14)%94)for i in range(len(V))]));V
'l:?AFEWXjAC:?EWQQ];@:?W,49CWbbZW@C5WD,:.XZ`cXThcX7@C : :? C2?86W=6?WDXX.XXj'