In any programming language that existed before this question was asked, write a program (not a function) that outputs the characters Hello world! followed by a newline. Your program:

  • should not use any character more than once (including whitespace)
  • should only use ASCII characters
  • should not use any built-in libraries
  • should not get input (user, file, filename, system variable, internet, anything)
  • should not output anything else

Winner is whoever has the most votes after 14 days and abides to the six rules.

The sixth rule is that you cannot use H9+, HQ9+, HQ9+B, HQ9++, HQ9+2D, Hello, Hello+, Hello++, Hexish, CHIQRSX9+, or Fugue. Also, all answers which require implementations that are newer than this challenge must be marked as non-competing.

Disclaimer: This question was posted with the assumption that Hello world! with limited repetition did not cause any damage to your computer or your brain in the process of coming up with the answers.

  • if We are escaping character codes, can the "\" character be used more than once? – WallyWest Jan 19 '14 at 22:40
  • 4
    What about piet? – Victor Stafusa Jan 19 '14 at 22:48
  • @Victor "should only use ASCII characters" – Timtech Jan 19 '14 at 22:58
  • 3
    That was a great puzzle, and I enjoyed doing it :-). – Konrad Borowski Jan 20 '14 at 20:38
  • 8
    “should only use ASCII characters” — what a draconian restriction. That removes an entire class of languages that don’t happen to use ASCII. – Timwi Jan 23 '14 at 18:49
up vote 30 down vote accepted

Perl 6 (29 28 characters)

This was somewhat annoying, but I finally managed to make a program for this task. Thanks go to the great #perl6 community, for helping me with this task. It took me two hours, hope you enjoy. The output is completely up to specification, including a newline.

Q[@A`DO world!]~|<HeLhg>

There are four tokens of interest.

  • say

    This outputs the argument with new line at end. The new line after the command itself is needed as a space replacement.

  • Q[@A`DO world!]

    This is the first string. Q[] is for raw strings (like r"" in Python). It can take any delimiter (or pair of them), in this case []. In this case, I use this for quotes, I don't need raw string behavior.

  • ~|

    This is stringwise (~) bitwise or (|) operator.

  • <HeLhg>

    <> is list literal, which takes space separated list of elements. In this case, it has one element, and used as a scalar, it gives a string.

  • 3
    Amazing! I need to get on learning. Some Perl 6 syntax! I agree with your comment too, was definitely a fun problem! – Dom Hastings Jan 20 '14 at 20:42
  • 4
    Woah... my mind is blown :O +1 – Doorknob Jan 21 '14 at 22:12

Perl 5 with -M5.010, 29 bytes

x2,q(O world!)^$"

Try it online!

I've gained a lot of knowledge since I first attempted this. Still not as short as the other answers, but the best I can come up with!


v! dloewrH

Right now, it doesn't have a trailing newline, but I think that's fixable

Edit: This code might print a trailing newline (>1/64 chance), but it has a much higher chance of putting random garbage at the end. I figure that this is the closest I'll get with the trailing newline, since I've run out of redirecting chars <>?^v. The problem with befunge is that you can't insert newlines as literals or with escape sequences.

! dloewrH

Also, if you think that I'm using multiple newline characters, the first is a formfeed, then a linefeed, then a vertical tab, and finally a carriage return, therefore they're still distinct ASCII characters.

  • 1
    Ha, I see. Why didn't I think of using a wraparound string literal... clever. Btw, according to the B98 spec, both B93 and B98 only ever support {CR, LF, CRLF}, but I guess that'd be a bit picky to complain about. :P (what codepoint is 'newline' though?) – FireFly Jan 20 '14 at 7:12
  • Concerning the first program, If your interpreter adds a bunch of spaces at the end of your string (80 grid width), it prints garbage, but if it does as expected, it prints no newline. – Justin Jan 20 '14 at 7:13
  • 1
    You could print the newline by changing to Befunge 98. a (evaluated) is the value of 10, so you could somehow put that in there. – Justin Jan 20 '14 at 7:15
  • @Quincunx I'd gladly switch to Befunge 98 if I knew where to find a compiler for it :) I've been using as my compiler. Do you know where I could find a Befunge 98 compiler? – Zaq Jan 20 '14 at 14:53
  • 2
    @FireFly You are correct on that, the answer is invalid per official specification. – Erik the Outgolfer Sep 30 '16 at 14:24

Perl 5.10+: 24 chars

say+He,YZX^q(567 world!)

OK, I think this is as short as it gets in Perl.

Run with perl -M5.010 (or just perl -E) to enable the Perl 5.10+ say feature.

  • Seriously impressed! I spent ages trying to get around the lls... – Dom Hastings Jan 24 '14 at 8:35

Golfscript 42 33

I might as well golf this, considering that I had to fit some of the code and all of the data in the same block with no way of delimiting the two I think this is a pretty short result. Unlike my first submission the block code is now a fully integrated part of the data, thus {1 do not only begin the block and put a 1 on the stack, it is also the data that defines the H, and so forth. The array creation now includes the empty input string, which means that I don't have to crop the beginning as there is only one character between the empty string and the H, that character is cut away when I take every second character, and the empty string eventually is output as nothing.

{1wZ$Qei^Ak 3h-)ulmsogr7}.`*]2%n+

Online demo:

[{1$^(r iFNGDJUHv98oIMgtplbh4m}.`\*]6>2%n+

Defines a code block. Makes a copy of the code block and converts it to string. Uses the code block to iterate over the string. For each iteration the code will make a copy of the previous char value, xor it with the current char value, and subtract 1. The resulting string then has the first 6 characters removed, and every second character removed. Finally a line feed is appended.

"r iFNGDJUHv98oIMgtplbh4m" is just two undeclared variables, they do nothing, but they are carefully constructed to produce the desired result.

Online demo:

Befunge-98, 34 31 bytes


Try it online!

Uses quite a few different methods to avoid duplicated characters.

First, we use wrapping string literal to avoid using two "s. This adds " world!" to the stack.

Going left on the second line, we add 9 to the extra f to make the o of the "Hello". We get the character from cell 5,0 (l) and then duplicate it. The ' is used to fetch the letter e. Multiply 9 by 8 to get 72, the ASCII value of H. We then print it everything using ck,, and flip the direction with the > to reuse the , to print the newline (a).

  • Very good but this challenge is without the comma. – Ørjan Johansen Feb 19 at 4:46
  • Oh lol, that makes it easier... Thanks @ØrjanJohansen – Jo King Feb 19 at 4:48
  • You have two of + and d. – Ørjan Johansen Feb 19 at 5:14
  • @ØrjanJohansen oops. should be fixed now – Jo King Feb 19 at 5:21

Vim 7.3, 18 keystrokes


Copies the string Hello world from this helpfile, which unfortunately has been removed in never versions of Vim.

  • According to this, Keystrokes like <Esc> and combinations involving the Ctrl-key count as one byte – oktupol Feb 20 at 8:16

Elixir, 37 bytes

IO.puts~c(He#{[?n-2,108]}\x6f world!)

Try it online!

I can't guarantee that this would have worked back in 2014 when this challenge was posted, and Elixir was still pre-1.0 (and thus, whether it is formally "competing", but looking at their release notes, I think it should be OK). Anyway, I'm happy that I finally found a valid solution to this task using a conventional general purpose language other than Perl!


IO.puts     #Print with trailing newline
~c(...)     #Sigil: charlist with interpolation
He          #Start of literal string...
#{...}      #Interpolated block
[?n-2,108]  #A list of codepoints for 2 'l's
\x6f        #Hex code for 'o'
world!      #...and done!

Stax (non-competing), 8 bytes


Try it online!

Just a compressed string literal. Luckily Stax lets me go without the closing backtick.

Your Answer

By clicking "Post Your Answer", you acknowledge that you have read our updated terms of service, privacy policy and cookie policy, and that your continued use of the website is subject to these policies.

Not the answer you're looking for? Browse other questions tagged or ask your own question.