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In a language of your choice, write a program that exactly outputs the characters Hello world! followed by a newline. The code:

  • should not use any character more than twice (alphanumeric, symbol, whitespace...anything)
  • should not use any external resources
  • should not use any user input
  • should not output anything else

An example of a valid python program:

print("He%so world!"%(2*'l'))

An example of an invalid python program (the character 'r' is used three times):

print("Hel"+chr(108)+'o world!')

Winner is whoever has the most votes after 14 days.

EDIT: A winner has been chosen! Thanks all for your work on this question!

share|improve this question
What about the repeated letter o in the "valid" python example. There also these:- " ' ( ) –  Adam Speight Jan 17 '14 at 16:35
@AdamSpeight what do you mean? The letter is only used twice, as per the specs. –  Josh Jan 17 '14 at 16:37
@AdamSpeight ... which is literally the same. –  VisioN Jan 17 '14 at 16:42
I think you mean a character should not appear more than twice, that is, it should not be repeated more than once. –  Michael Kay Jan 17 '14 at 18:15
I guess brainfuck is out of the question... –  Jubobs Jan 17 '14 at 18:26

68 Answers 68

up vote 52 down vote accepted

Ruby (1.9+)

Since this is a popularity contest let's try to not use ANY of the characters from 'Hello world!' while still using other characters only a maximum of two times:


It's 40 chars btw.


And this one uses unicode magic.


  • While the orignal characters appear elsewhere (unlike the ruby example), the printed string contains only non-ascii characters.
  • Two from the three spaces are actually tabs, so there are no utf-8 characters that appear more than 2 times
  • As binary some of the octets do appear more than 2 times, hopefully that's not against the rules. I'm trying to resolve them though.


echo '𝓗𝐞𝑙𝒍𝓸 𝓦𝗈𝖗𝖑𝘥¡'|iconv -t  asCIi//TRANSLIT

For those who don't have a proper font installed it looks like this:

code as image

Here is the hexdump:

00000000  65 63 68 6f 20 27 f0 9d  93 97 f0 9d 90 9e f0 9d  |echo '..........|
00000010  91 99 f0 9d 92 8d f0 9d  93 b8 e2 80 8a f0 9d 93  |................|
00000020  a6 f0 9d 97 88 f0 9d 96  97 f0 9d 96 91 f0 9d 98  |................|
00000030  a5 c2 a1 27 7c 69 63 6f  6e 76 09 2d 74 09 61 73  |...'|iconv.-t.as|
00000040  43 49 69 2f 2f 54 52 41  4e 53 4c 49 54 0a        |CIi//TRANSLIT.|

You have to run it on a machine where the default charset is utf-8. I tried on an OSX10.8 using iTerm2 with the following environment:

bash running in iTerm2

PHP 5.4

This uses zLib: (unfortunately it does uses the characters e and o)



00000000  3c 3f 3d 67 7a 75 6e 63  6f 6d 70 72 65 73 73 28  |<?=gzuncompress(|
00000010  27 78 9c f3 48 cd c9 c9  57 28 cf 2f ca 49 51 e4  |'x..H...W(./.IQ.|
00000020  02 00 21 71 04 68 27 29  3b                       |..!q.h');|


Here is the ruby 2.0 code I used to test for duplicates:

p [d.split(//),d.unpack('C*')].map{|x|x.inject(Hash.new(0)){|i,s|i[s]+=1;i}.select{|k,v|v>2}}
share|improve this answer
While I always appreciate Unicode cleverness, your bash attempt doesn't seem to satisfy the question's specification. "write a program that exactly outputs the characters Hello world! followed by a newline" –  FireFly Jan 17 '14 at 21:07
@FireFly: it does satisfy it. iconv with the target encoding ascii//translit will transliterate the unicode characters to basic ascii. And of course echo will add the newline, so this one fits the spec (if we don't consider the similarity of the octets) –  SztupY Jan 17 '14 at 21:10
On my system I get Hello World? instead of Hello World! –  marinus Jan 17 '14 at 21:20
@SztupY oh, you're right, my bad. Very clever, I like it! –  FireFly Jan 17 '14 at 21:21
How many bonus points would you get if your duplicate-checker also conformed to the repeating spec? :-) –  corsiKa Jan 17 '14 at 22:10

HQ9+, 1 char


keeping it simple :)

share|improve this answer
HQ9+ outputs a comma though ;) –  Josh Jan 17 '14 at 15:48
I'd still keep your answer out...it is a popularity contest after all, rules are for the wind! –  Josh Jan 17 '14 at 15:53
@Josh This is one of the rare events where I miss the downvote button on comments. If we throw away rules there is nothing left to justify the contest at all. –  Howard Jan 17 '14 at 16:24
@Howard I feel dirty. I upvoted yours and Josh's comment –  Cruncher Jan 17 '14 at 17:03
All print Hello World questions are actually who can submit a HQ9+ answer faster questions. –  totymedli Jan 18 '14 at 5:49

C, 192 chars

/*$$@``*/ATION_[]={9.};main(BBCDDEEFFGGHJJKKLLMMPPQQRRSSUUVVWWXXYYZZabbdefgghhjjkkmpqqsstuuvvwxyyzz) {printf("He%clo \

Since this isn't golf, I decided to have some fun and try to use every character exactly twice (while putting as few as possible in a comment, because that's boring). I realise that I didn't do terribly well, since my code contains a ton of boring "dead" code too (not in the literal sense, but in the sense of placeholder characters just used in order to fullfil the requirement). Anyway, this was surprisingly hard (but fun) with the two-character limitation, so unfortunately I couldn't come up with anything more interesting. It did give me an idea for a new problem though...

(Updated per @ugoren's comment.)

share|improve this answer
Creatively impressive. I like it. –  Josh Jan 17 '14 at 22:48
The slash `\` ending lines three and four make it a line continuation, not newline. And line four is terminated by a EOF, making it legal. –  Josh Jan 18 '14 at 6:02
I think you can easily uncomment . by using it for fractions. Also you can declare an array and use []. –  ugoren Jan 19 '14 at 15:18
@ugoren good call about .; I only thought about using it for struct access. <s>As for array declarations, I'm out of ,s due to the printf call, and I'm also out of ;s, so I'm not sure how I could declare one.</s> Duh, I could replace ATION_... –  FireFly Jan 19 '14 at 15:29

Vim command (18 keystrokes)

iHeEsc3alEscio WorRightd!Enter

Doesn't repeat any keystroke more than twice.

It kinda violates the "user input" rule since it's still the user that needs to input that sequence, but I suppose if you store it as a macro or an nnoremap beforehand it would count, since you're just running it without explicitly doing any input to make it happen.

It also requires nocompatible to be set, which may count as using external resources, so I have provided another variation below:

Vim command (21 keystrokes)

iHeEsc3alEscio WorCtrl+[$ad!Enter

This variation doesn't require nocompatible to be set, although it does work around using Esc three times by using Ctrl+[ in its place.

share|improve this answer
If you're talking about the characters in Right, Esc, and Enter, they're not literally those characters. Vim deals in keystrokes, which I am deeming equivalent to characters for the purposes of this contest (and the "don't repeat more than twice" rule). I only use the i keystroke twice, and the <Right> keystroke once. As for E, I never use it at all - but I do use <Esc> twice and <Enter> once. –  Joe Z. Jan 17 '14 at 19:11
Now I'm disappointed that Emacs doesn't have a M-x hello-world command... –  RemcoGerlich Jan 17 '14 at 19:34
Even if it did, that's three ls. –  Joe Z. Jan 17 '14 at 19:35
You should note that you have to :set nocompatible. –  jazzpi Jan 19 '14 at 14:15
Amazing, but myself find using Right not very vim-y. –  gefei Jan 19 '14 at 16:11

You have to use more expressive languages.

Chinese,  6  4   3 chars


Running google translate on this produces Hello world!

(thanks @sreservoir and @Quincunx for the update)

share|improve this answer
+1 for sheer cheek. –  Joe Z. Jan 19 '14 at 21:18
+1 for rule bending... "In a language of your choice..." –  WallyWest Jan 19 '14 at 22:54
Love it. But how exactly is that a program? –  Pierre Arlaud Jan 20 '14 at 8:42
Actually you can look at it as a program in a google translate language - for Chinese as its sub-language :) –  Tomas Jan 20 '14 at 8:44
can be golfed down further to 喂世! at the expense of ... well, nothing more is really being expended. –  sreservoir Jan 20 '14 at 23:40

Powershell, 20

"He$('l'*2)o world!"
share|improve this answer

Piet-- No characters whatsoever!

Hello world in Piet

share|improve this answer
I would consider the codels as "characters". –  Paŭlo Ebermann Jan 17 '14 at 21:16
@PaŭloEbermann What would you consider to be a unique codel? EG different shapes? colors? sizes? some combination thereof? –  Approaching Darkness Fish Jan 19 '14 at 19:19
@ValekHalfHeart the definition of a unique codel is given in the specs of the language: it s a block of codel that could be simplified as a single colored pixel. –  plannapus Mar 7 '14 at 9:30
@plannapus In that case I don't this challenge is technically possible in Piet. I may come up with something creative though. –  Approaching Darkness Fish Mar 7 '14 at 17:57
@ValekHalfHeart oh it wasn t a criticism of this answer: i love it! This challenge was not a codegolf anyway. –  plannapus Mar 8 '14 at 7:44

Perl, 29 characters

This answer includes x-rated clogs!


Perl, 23 characters

Shorter, but no porno shoes. :-( Same basic idea though...

say'0@@lo World!'^"x%,"

Perl, 20 characters


say"Hello Wor\x6Cd!"
share|improve this answer
Um....kinky? +1 :) –  Josh Jan 18 '14 at 14:32

Python 3 [38 bytes]

exec('import '+chr(95)*2+"h\x65llo__")

I wouldn't consider import __hello__ as an external resource.

share|improve this answer

Scala: 34 29 characters

I'm proud of myself for this one:

printf("He%c%co world!\n",108,108)

Had a really hard time overcoming duplicate 'l's, 'r's, quotation marks and brackets. Then I discovered the old Java printf function, which will happily convert numbers to letters when given the %c format specifier.


MrWonderful did a wonderful thing by pointing out that a whole bunch of characters can be saved by using up my second 'l' manually in the string!

printf("Hel%co world!\n",108)
share|improve this answer
@KCaloux, Since you are allowed up to 2 'l's, wouldn't printf("Hel%co world\n",108) at 28 be even better? –  MrWonderful Jan 17 '14 at 19:11
@MrWonderful I think you're absolutely correct! (Also I just realized that I forgot to include the '!') –  KChaloux Jan 17 '14 at 19:17
From what I understand, this isn't a valid entry, though a good attempt at it. printf contains a r as does world. Same goes for the letter o which is used more than once. This is based on my interpretation of the following statement from the OP "An example of an invalid python program (the character 'r' is used three times): print("Hel"+chr(108)+'o world!')" –  JAnderton Jan 18 '14 at 9:58
@JAnderton I had a ruby program parse out my script to make sure there were no characters included more than twice. Read it again. There are 2 rs, not 3. One in "printf" and one in "world". The reason the python one is invalid is because it includes chr –  KChaloux Jan 18 '14 at 16:36

Perl: 34 characters

$_="He12o wor3d!

Sample run:

bash-4.1# perl -e '$_="He12o wor3d!
> ";s{\d}{l}g;print'
Hello world!

(Not a big deal. Posted just to use at least once in my life s/// with those fancy delimiters.)

share|improve this answer

Sclipting, 11 characters


I saw this beautiful HelloWorld program on esolang's Hello World program list.

share|improve this answer
Whoa! Congratulations, you are the first person ever to post anything about any of my esolangs outside of esolangs.org :) (or at least the first I found out about) –  Timwi Jan 20 '14 at 12:30

PHP, 33 chars

I just love how much PHP is forgiving and understanding!

<?=Hel.str_rot13("yb jbe").'ld!';

Before it was deleted (or if it's still there, I'm totally blind), I saw a comment saying "No brainf*ck? :D". Well, it is pretty much impossible to write a solution in BrainF*ck, as you know. But I managed to code this, just for the lulz.


If you don't have a BF interpreter, the code above just prints the PHP one :P

share|improve this answer
I didn't know even a code like this is valid! Php tag isn't closed and string Hel isn't surrounded by quotes. Also I've never heard about str_rot13 before. –  Aycan Yaşıt Jan 17 '14 at 18:56
@AycanYaşıt the closing php tag is not required on EOF, and if you put a string without quotes it assumes it is an undeclared constant with the same content as its name and gives a warning –  Einacio Jan 17 '14 at 19:25
You can avoid the warning (and save the first .) by putting the Hel before the <?=. –  Paŭlo Ebermann Jan 17 '14 at 21:23
@PaŭloEbermann Hel<?=str_rot13("yb jbe")?>ld! –  MirroredFate Jan 17 '14 at 23:47
@PaŭloEbermann I would say that using that is like cheating, since it's not pure PHP anymore. –  Vereos Jan 18 '14 at 0:43

Ruby: 27 characters

puts [:Hel,'o wor',"d!"]*?l

Sample run:

bash-4.1# ruby <<ENDOFSCRIPT
> puts [:Hel,'o wor',"d!"]*?l
Hello world!

Ruby: 25 characters

(Based on Vache's comment.)

puts 'He'+?l*2+"o world!"

Ruby: 23 characters

(Copy of Danko Durbić's Powershell answer.)

puts"He#{?l*2}o world!"
share|improve this answer
puts 'He'+'l'*2+'o world!' is one character shorter! –  Vache Jan 17 '14 at 16:38
But has 6 “'”'s… –  manatwork Jan 17 '14 at 16:50
haha I was so focused on letter characters that I never noticed that. never mind! –  Vache Jan 17 '14 at 16:53
Remove the space after puts and make it 23. -- puts"He#{?l*2}o world!" –  Sampriti Panda Jan 17 '14 at 17:52
@SampritiPanda, p includes quotes in the output. I prefer to keep strictly with the required output format. But you are right, the space is not needed. Thank you. –  manatwork Jan 17 '14 at 18:17

HTML Fiddle - 21 characters

Hel&#108;o World!<br>
share|improve this answer
Does that include the trailing newline? –  Josh Jan 17 '14 at 18:32
Doh...missed that requirement! I'll add a <br> in there. –  Briguy37 Jan 17 '14 at 18:36
@netinept :It asked for a newline, not a \n so I'd say <br> counts –  Chris Jan 17 '14 at 22:54
But the character r is repeated in the solution. Did I misinterpret the requirements? –  JAnderton Jan 18 '14 at 9:59
"l" and "o" too, but each character can be used twice at most. –  xem Jan 18 '14 at 14:04

C - 43 Characters

main(){printf("Hel%co World!%c",'k'+1,10);}


Hello World!

Character Counts

' ' Count: 1    '!' Count: 1    '"' Count: 2    '%' Count: 2    ''' Count: 2
'(' Count: 2    ')' Count: 2    '+' Count: 1    ',' Count: 2    '0' Count: 1
'1' Count: 2    ';' Count: 1    'H' Count: 1    'W' Count: 1    'a' Count: 1
'c' Count: 2    'd' Count: 1    'e' Count: 1    'f' Count: 1    'i' Count: 2
'k' Count: 1    'l' Count: 2    'm' Count: 1    'n' Count: 2    'o' Count: 2
'p' Count: 1    'r' Count: 2    't' Count: 1    '{' Count: 1    '}' Count: 1
share|improve this answer
Don't you need main etc? –  FireFly Jan 17 '14 at 19:28
@FireFly I guess so! It did say to write a program. –  Kirk Backus Jan 17 '14 at 19:36
That's C but not C++. C++ does not have implicit int (and you can't spare another i). –  Ben Voigt Jan 17 '14 at 19:52
@BenVoigt Okie dokie! –  Kirk Backus Jan 17 '14 at 19:56

JavaScript, 66 characters


Inspired by FireFly, every character used by this code is used exactly twice.

share|improve this answer
I think you are allowed to use some characters just once, and you can drop the comment. –  Jan Dvorak Jan 18 '14 at 3:19
@JanDvorak - well, sure he could have done it that way - but I think this solution is deserving of an upvote for the sheer bloodymindedness of using each and every character exactly twice. :-) –  Bob Jarvis Jan 19 '14 at 1:22
+1, but it's easy to use each character exactly twice if you just add gibberish as a comment. –  Camilo Martin Jan 19 '14 at 7:32

JavaScript [37 bytes]


Too primitive isn't it?

share|improve this answer
Where’s the newline? –  Christopher Creutzig Jan 17 '14 at 20:26
@ChristopherCreutzig Sorry, forgot it. Now it is in place. –  VisioN Jan 19 '14 at 0:46


return  200 "He&#x6clo wo&#x72ld!\n";

In action:

% curl -6 http://localhost/ | lynx -dump -stdin
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100    21  100    21    0     0  20958      0 --:--:-- --:--:-- --:--:-- 21000

   Hello world!

share|improve this answer
There are 4 spaces in this solution... –  Josh Jan 17 '14 at 20:54
@Josh, actually, there are 5. But couldn't you consider that two of the first four are tabs, and then the last one is a non-breakable space? :-) –  cnst Jan 17 '14 at 20:58
That works for me! –  Josh Jan 17 '14 at 21:00
@Josh, actually, now that we're using HTML, no more need for set. This only has 3 spaces now, any one of which could be a tab! –  cnst Jan 17 '14 at 21:13
Very nicely done. –  Josh Jan 17 '14 at 21:15

Emacs Command (15 keystrokes)

He<Ctrl-3>l<Left>o wor<End>d!<Enter>

If that vim answers is legal then this must be too :)

Joking aside, macro it can become too :)

More nonsense aside, I can probably squeeze some more, but this seems to be good enough for the time being (since it beats vim).

P.S., please ignore all my nonsense (I (rarely, but)use vim too!).

share|improve this answer
I still think vim > emacs. –  Joe Z. Jan 18 '14 at 5:07


From the esolang wiki:

enter image description here

And you can listen to the source code.

share|improve this answer
I'd say this is invalid. I can see more than 4 middle c's in the right hand. –  Quincunx Jan 17 '14 at 21:47
Not to mention the string of four consecutive G's in the 9th measure. –  Joe Z. Jan 17 '14 at 21:53
Did you write this, or only render it? Given that you link to the esolang archive's MIDI. –  FireFly Jan 17 '14 at 22:02
-1 for plagiarism. This is from esolang wiki. You do not cite it. Edit: reverted, now the esolang wiki is cited. –  Quincunx Jan 17 '14 at 22:13

Befunge 98

a"!dlrow ol":'e'Hck,@

Here is a version where every character appears twice.

bka!e:dw"H@!dlrow  ol":'e'Hbk,a,@

Leaves a bunch of junk on the stack.

As a bonus, every single character has something done with it by the IP.

share|improve this answer

Actually I don't like cheating :P


print("!dlrow os%eH"[::-1]%('l'*2))
share|improve this answer
You should specify that it's for python2. In python3 the you get the reversed string as output and then a TypeError. –  Bakuriu Jan 18 '14 at 7:09
For use in Py3K argument of print must by enclosed in parenthesises. print("!dlrow os%eH"[::-1]%('l'*2)) work in both (Python2 and Py3K) versions. –  AMK Jan 19 '14 at 16:24



o world!'n/"l"*

Substitutes two newlines (fortunately the third one, needed for the substitution, is provided by the built-in n), using both types of string literal to avoid quadruplicate copies of a quote mark. Since l is the only character which occurs more than twice in the original string, it's not too hard.

share|improve this answer
You forgot the "!". –  Howard Jan 17 '14 at 16:27
@Howard, missed it. Oops. –  Peter Taylor Jan 17 '14 at 16:31
The letter o is repeated also –  Adam Speight Jan 17 '14 at 16:34
@AdamSpeight: There is only twice the letter o. The rules say that it's not allowed to have a character more than twice. –  ProgramFOX Jan 17 '14 at 16:35


In C, given these rules, we can only have one #define (because of i and n) and at most two function calls OR definitions (( and )).

I presume there's pretty much only one way to do it (though I'm probably wrong):

main(){puts("Hello w\x6fr\154d!");}
share|improve this answer
You still need to output the trailing newline. Doing this challenge in C is difficult... –  Josh Jan 17 '14 at 16:55
@Josh I just have to use puts() instead of printf(). –  Oberon Jan 17 '14 at 16:59
But what's wrong with o in world? –  VisioN Jan 17 '14 at 17:01
@VisioN In an old draft of the same code (before I realized how hard it actually was to write such a program) I used another 'o' elsewhere. But this isn't code-golf, so I guess it doesn't have to be fixed. –  Oberon Jan 17 '14 at 17:08
In fact, I'm not sure why every answer is displaying a character count. –  Oberon Jan 17 '14 at 17:10


printf 'Hel\x6co world!\n'

Cred @manatwork

echo $'Hel\x6c\x6f world!'
share|improve this answer
The first one has 3 “e”'s and 3 “o”'s. –  manatwork Jan 17 '14 at 18:42
@manatwork: Gag; thanx ;) –  Sukminder Jan 17 '14 at 18:43
In Bash you may skip -e by using the special $'…' syntax: echo $'Hel\x6c\x6f world!'. –  manatwork Jan 17 '14 at 18:48

C - 46 Characters

main(){printf("He%clo wor%cd!\x0d",'l',108);}

Prints out:

Hello world!

share|improve this answer
If you're aiming for golf, main(){printf("He%clo world!%c",108,10);} should work, and saves you a few chars. –  FireFly Jan 17 '14 at 19:23
@FireFly you're right, you'd save me 3 characters. Your suggestion works perfectly, too. –  Phillip Kinkade Jan 17 '14 at 19:43


32 Chars

Note how I am not using a character more than twice, since l != L

He<?=strtolower("LLO WOR");?>ld!

Also note that, despite of Stack Overflow deleting it in the representation, there's a line break after the !.

share|improve this answer
You are using three spaces, but I guess this can be fixed removing the ones near the PHP tags! :P –  Vereos Jan 18 '14 at 1:05
That was fast, although I realized before of reading your comment (from another answer actually) –  Francisco Presencia Jan 18 '14 at 1:07
Isn't the output "H" supposed to be uppercase? –  David Cary Jan 18 '14 at 2:47
Completely true, missed that also ): –  Francisco Presencia Jan 18 '14 at 2:49


set $i l;
return 202 "Hel${i}o world!\n";

In action:

opti# curl -6v "http://localhost/"
* About to connect() to localhost port 80 (#0)
*   Trying ::1...
* connected
* Connected to localhost (::1) port 80 (#0)
> GET / HTTP/1.1
> User-Agent: curl/7.26.0
> Host: localhost
> Accept: */*
< HTTP/1.1 202 Accepted
< Server: nginx/1.4.1
< Date: Fri, 17 Jan 2014 18:02:08 GMT
< Content-Type: application/octet-stream
< Content-Length: 13
< Connection: keep-alive
Hello world!
* Connection #0 to host localhost left intact
* Closing connection #0
share|improve this answer
Unfortunately your code has three e's and three l's! –  Josh Jan 17 '14 at 18:13
One of the duplicate l's can be removed easily. e is harder, unless nginx is case-insensitive –  SztupY Jan 17 '14 at 18:20
Don't forget the spaces! –  Vereos Jan 17 '14 at 18:52
And 3×'r', as well –  Joel Purra Jan 19 '14 at 14:22

XQuery (19 chars)

"Hello Wor&#x6C;d!"
share|improve this answer

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