# Ah, why is there a bug in my program?

This challenge is inspired by @LuisMendo's MATL answer to my "binary multiples" challenge.

Pick a challenge that is open and that has been posted before this one; let me call it the "linked challenge". The linked challenge must be a challenge whose task involves producing output.

Write the shortest code possible that satisfies the following restrictions:

• Your code must contain the characters b, u and g in your program, in this order and consecutively (case-insensitive, so "bug", "BUG", "Bug", "bUg", ... are all fair game.);
• Your code must not contain the letters b, u and g more than once (case-insensitive);
• Your code should be a valid submission for the linked challenge;
• When any subset of the (case-insensitive) characters bug are removed, your program no longer fulfils the task of the linked challenge. This may happen because your program now produces the wrong output (i.e. fails test cases), because it halted with an error, because it runs indefinitely and never returns (if this is the case, be prepared to prove your program runs indefinitely), etc.
• Your code should not be an integral copy - nor a trivial modification* - of a submission that already exists in the linked challenge (for example, you may not copy @LuisMendo's MATL answer to my "binary multiples" challenge);

# Input

Your program takes input as per the specs of the linked challenge you choose.

# Output

Your program, in its correct state (i.e. with a bug**), must abide by the output specs of the linked challenge you choose.

* This is subjective so I appeal to your common sense; any imaginative modification should be fair game, even if in retrospective it is "trivial". This "no trivial modifications" rule will be "enforced" by me downvoting answers I think disrespect this...

** Sit down, take a moment to let this sink in. Your program has a bug. And yet your program is correct.

This is so shortest submission in bytes, wins! If you liked this challenge, consider upvoting it! If you dislike this challenge, please give me your written feedback. Happy golfing!

• @a'_' I do not understand how that challenge presents a loophole; can you please clarify? – RGS Mar 17 '20 at 15:34
• @RGS Interesting challenge. I wonder if the challenge can be more focused by specifying just 1 linked challenge to solve. As of right now, my effort is divided between picking a linked challenge, and golfing/solving the linked challenge. – Surculose Sputum Mar 17 '20 at 15:48
• @ouflak nope, the three characters must be really really consecutive :) so that they spell "bug" :) – RGS Mar 17 '20 at 15:55
• It's impossible to do this in brainfuck... – S.S. Anne Mar 18 '20 at 1:22
• Python has a built-in constant called __debug__ which is True by default. Removing some of its bug will obviously be an error. Though I can't find a suitable challenge for that... – Bubbler Mar 18 '20 at 1:49

# Japt, 4 bytes

Challenge: Output with the same length as the code

BUG³


Test it

## Explanation

B, U, and G are variables for 11, the input, and 16 respectively.

When applied to a number, ³ brings it to the third power.

In Japt, only the last expression is outputted, so only $$\16^3 = 4096\$$ is outputted, which is the same length as the code (4).

Since B and U are ignored, removing them have no effect on the output. However, their removal changes the length of the program, making it invalid. Removing G raises either the input (U) or 11 (B) to the third power. While $$\11^3 = 1331\$$ is 4 bytes, the program B³ is only two bytes, making the output invalid. The variable U defaults to 0 when there is no input given, and $$\0^3 = 0\$$, which is only one byte long.

• This seems like a pretty clever answer. Why did you delete it? – ouflak Mar 17 '20 at 20:19
• @ouflak the first version had a bug, I deleted it to give me some time to edit it – Gymhgy Mar 17 '20 at 20:21
• @EmbodimentofIgnorance ba-dum crash! – S.S. Anne Mar 18 '20 at 1:37
• Fail ³ also work – l4m2 May 22 '20 at 14:59

# Polyglot, 31 bytes

This is a full program, as per the original challenge requirements.

print('Hello, World'+'bug!'[3])


Try it in JavaScript (V8)!

Try it in Python!

# JavaScript (ES7), 47 bytes

Linked challenge: How many petals around the rose

a=>a.map(n=>t+=n**3&parseInt('bug',35)%9,t=0)|t


Try it online!

### How?

This is a port of my Python answer to the linked challenge. This answer requires a bitwise AND with a constant, which happens to be $$\6\$$.

This $$\6\$$ is obtained with the cumbersome parseInt('bug',35)%9 and removing any subset of characters from bug would produce a different (and therefore invalid) constant.

   s   | parseInt(s, 35) | mod 9
-------+-----------------+-------
'bug' |      14541      |   6
'ug'  |       1066      |   4
'bg'  |        401      |   5
'bu'  |        415      |   1
'g'   |         16      |   7
'b'   |         11      |   2
'u'   |         30      |   3
''    |        NaN      |  NaN

• 'bug'.length*2  is an alternative – Surculose Sputum Mar 17 '20 at 16:14
• @SurculoseSputum That's actually not possible: there's a 'g' in 'length'. – Arnauld Mar 17 '20 at 16:28
• That's unfortunate :( I was thinking of Python when writing that comment. – Surculose Sputum Mar 17 '20 at 16:30
• a=>a.map(n=>t+=n**3&('bug'[2]&&6),t=0)|t for 40 bytes – Gymhgy Mar 17 '20 at 20:06
• @EmbodimentofIgnorance There's also &!!'bug'[2]*6 for 39 bytes, but I think I'll stick with my sub-optimal version for this answer, so feel free to use it in another one! – Arnauld Mar 17 '20 at 20:14

# C (gcc), 156 bytes

Answer to 99 bugs in the code. Not competitive, but funny.

#define S"%d bugs in the code\n"
d;f(i){for(i=99;i;i=d)printf(S S"Take one down and patch it aro\x75nd\n"S"\n",i,i,d=(d=i+rand()%21-16)<0?0:d);printf(S,0);}


Also beats the C solution there.

Try it online!

• +1 for the "right" challenge to solve. – Bubbler Mar 18 '20 at 2:41

# Triangular, 6 bytes

Linked to Challenge: Shortest code to produce infinite output

bug>%<


Try it online!

• Basically the same thing works in Hexagony, probably other layout languages, too. – FryAmTheEggman Mar 17 '20 at 18:27

# Python 3, 24 bytes

while __debug__:print(1)


Try it online!

Linked challenge: Shortest infinite loop producing output

Uses the fact pointed out by @Bubbler:

Python has a built-in constant called __debug__ which is True by default. Removing some of its bug will obviously be an error. Though I can't find a suitable challenge for that...

• Removing the bu from your answer still gives the correct answer -- the rules state that any subset of the characters in bug being removed should cause the problem to return something different, not just the bug as a whole!! – Value Ink Mar 17 '20 at 21:49
• @ValueInk I changed the language and used python instead. – Lyxal Mar 18 '20 at 3:56
• Quoting my spec, "The linked challenge must be a challenge whose task involves producing output." – RGS Mar 18 '20 at 6:51
• @RGS that's been fixed now. I've really lost the ability to read challenges today. :P – Lyxal Mar 18 '20 at 6:57
• I really like the use of __debug__, however simply using "bug"[2] should be shorter (and more boring). TIO. – Surculose Sputum Mar 18 '20 at 10:16

# APL (Dyalog Extended), 6 bytes

×'BUG'


Try it online!

Prints 1 1 1\n, 6 bytes in total.

In regular APL, monadic × is Signum for numbers (-1 if negative, 1 if positive, 0 if zero). Extended provides an extended (no pun intended) definition for characters (-1 for lowercase, 1 for uppercase).

Because numeric arrays are printed with a space between items, deleting one char out of BUG will remove two bytes (<space>1) from the output, thus failing to solve the challenge. Deleting two chars will remove four output bytes, and deleting all of them gives only a single newline.

# Zsh/Bash/others, 15 bytes

Challenge: Output with same length as code

echo BUG{1..3}


• The second submission is invalid because the linked challenge should produce output! – RGS Mar 18 '20 at 6:40
• Argh, thanks. Fixed. – GammaFunction Mar 18 '20 at 6:41

# CJam, 4 bytes

Challenge: Output with the same length as the code

It's working. But I still didn't manage a 3-byte solution.

BUG^


Try it online!

# Why it works

B    "Constant for 11";
U   "Constant for 0";
G  "Constant for 16";
^ "Bitwise XOR";


0 XOR 16 is 16, therefore it outputs 1116.

# Removing a single character

UG^


It just outputs 16 without other calculations.

BG^


It outputs 27 because 11 XOR 16 is 27.

BU^


It outputs 11 because 11 XOR 0 is 0.

## Removing 2 characters

CJam doesn't have implicit input, so all these programs would throw an error.

# Lua and perhaps a polyglot in concept, 2528 32 bytes

Along the lines of Arnauld's answer, linked to challenge Output programming language name.

print('\076\117\097 5.'..#'bUg')


Try it online!

Added 3 bytes Thanks to @RGS spotting the 'u' in 'Lua'
Added 4 bytes Thanks to @MariaMiller for the 'L' and the 'a' as well

• This is not a valid answer because the letter "u" appears twice in your code! – RGS Mar 17 '20 at 18:16
• @RGS, Oh my God. You're right! Let me fix this up. – ouflak Mar 17 '20 at 18:19
• @MariaMiller, Refresh your browser. Unless I'm misunderstanding your comment, RGS already pointed that out and I've already updated the answer. – ouflak Mar 17 '20 at 18:58
• According to the linked kata, your code cannot include any characters of the language's name, but case sensitive so it can be fixed: You can fix L and a with the same way you fixed u, and I just noticed that you can change bug to bUg or BUG or whatever and this will be alright. Sorry if I was confusing. – Steffan Mar 17 '20 at 22:26
• Didn't they realize that both l and A aren't banned in outputting the language name? 25 bytes – user92069 Mar 18 '20 at 6:11

# PHP, 16 bytes

echo'2=7'^'bug';


Try it online!

Omitting any of the letters in bug outputs a wrong string. However, it won't cause any errors so that error messages containing PHP can never be outputted. All PHP answers in that challenge exploit either PHP flags, which cannot contain the word bug, or PHP errors, which omitting a letter from bug could still result in an output that fulfils the requirements.

Create output twice the length of the code

# MathGolf, 6 bytes

╘╘BUG]


Try it online!

# 05AB1E, 4 bytes

Linked challenge: Output with same length as the code.

Port of Embodiment of Ignorance's Japt answer.

bug₄


Try it online!

# C (gcc), 26 bytes

f(){printf("bug"+2)&&f();}


Try it online!

• Maybe I'm missing something but your TIO link produces no output – RGS Mar 18 '20 at 17:07
• @RGS I forgot the footer. Hang on... – S.S. Anne Mar 18 '20 at 17:08
• Woops, I only noticed now... The character u shows up twice in your answer! – RGS Mar 20 '20 at 15:39
• @RGS Fixed..... – S.S. Anne Mar 20 '20 at 15:43
• why &&? then . – l4m2 Apr 22 '20 at 10:34

## Javascript, 8 characters

Linked question: Output with the same length as the code

bug=>1e7


Outputs 10000000, which has the same length as the program. Removing 1 or 2 characters would make it print the same thing, but wouldn't match the length of the program anymore. Removing all 3 is a syntax error.

# Ruby, 24 bytes

->n{(n+5+"bug".size)/10}


Try it online!

• What is the challenge this problem is linked to? – RGS Mar 17 '20 at 18:16
• Sorry, I accidentally deleted it. Added. – Steffan Mar 17 '20 at 18:17

Linked to challenge: Find the number of integers in the range from 1 to N that ends with 2

# Python 2, 95 $$\\cdots\$$ 39 35 bytes

Saved a byte (in a previous version) thanks to Maria Miller!!!
Saved a byte (in an other previous version) thanks to Surculose Sputum!!!

def f(n):print((n+len("bug")+5)/10)


Try it online!

• 74 bytes – Steffan Mar 17 '20 at 18:15
• @MariaMiller Nice one - thanks! :-) – Noodle9 Mar 17 '20 at 18:19
• 30 bytes – Steffan Mar 18 '20 at 16:47

Linked to challenge: Find the number of integers in the range from 1 to N that ends with 2

# C (gcc), 51 42 40 bytes

i;f(n){for(i=0;n+=2,"bug"[i++];);n/=10;}


Try it online!

# JavaScript (Node.js), 39 bytes

Linked Challenge: How many petals around the rose

a=>a.map(n=>t+=n**3&!!'bug'[2]*6,t=0)|t


Try it online!

Originally posted as a golf to Arnauld's answer.

# W, 6 bytes

Challenge: Output the same length as code

BUG"2*


Repeats the string "BUG" multiple times.

# Python 2, 13 bytes

print 'bug'*4


Try it online!

Prints bugbugbugbug\n.

# Python 2, 27 bytes

Solves Hello, World!

print'bugHello, World!'[3:]


Try it online!

Removing some of bug will chop off characters from the beginning of 'Hello, World!'.

• The middle answer isn't valid because the linked challenge has to produce output! – RGS Mar 18 '20 at 6:35
• I mean in my spec :) you have to pick a challenge where you have to produce output "The linked challenge must be a challenge whose task involves producing output." – RGS Mar 18 '20 at 6:43
• @RGS Oops, sorry, I missed the restriction. – Bubbler Mar 18 '20 at 6:43

# J, 7 bytes

>:Debug


Prints 1 as given, 2 doubled.

### How it works

Monadic >: is "increment" (add 1), dyadic >: is "greater or equal" (x >= y).

>:Debug    NB. increment 0; gives 1

>:Debug>:Debug
Debug>:Debug    NB. 0 >= 0; gives 1
>:                NB. increment it; gives 2


# J, 12 bytes

echo 6#Debug


Try it online!

Somewhat similar to Python, J has a stdlib variable Debug which is initialized to the number 0. 6# replicates the zero 6 times, and echo prints it. The output formatting is identical to APL's (space-separated numbers), so the output is 0 0 0 0 0 0\n.

Being a terse language, I suspect there could be a more suitable challenge for J which gives a shorter solution using Debug.

# C (gcc), 24 bytes

This one for real.

f(x){x=-(-x^!"bug"[3]);}


Try it online!

# Io, 18 bytes

Challenge: Output programming language name

(Joke ruiner over here, never mind.)

This errors (outputting the language name) when the bug is inside, and it doesn't error when any part of the bug is removed.

If you think that this uses the i character (taken from the question):

Note that this is case sensitive. I can still use the char 'b' because it's different from 'B'.

if("bug"size>2,iO)


Try it online!

## Explanation

        size       // Is the length of
"bug"           // the string "bug"
>2     // larger than 2?
if(           ,    // If so,
iO  // Access an undefined variable
) // Otherwise, do nothing


# Io, 19 bytes

Challenge: Output with the same length as the code

"bug"at(2)cos print


Try it online!

# Explanation

"bug"               // The sequence "bug"
at(2)          // The 3rd index of that
// (Out-of-bounds indexing returns nil)
// This returns an integer for an in-bound index
cos       // Find the cosine of that
// (Cosine over nil throws an error)
print // Print that value to STDOUT. (WITHOUT a newline)


# Io, 19 bytes

while("bug"at(2),0)


Try it online!

# Explanation

      "bug"         // Base string "Bug"
at(2)    // Try to access the 3rd item of the string
// (Out-of-bounds returns nil)
while(          ,   // While that's true:
// (So a string is always true and nil is always false)
0) // No action needed

• What does the last one solve? – user253751 Mar 18 '20 at 16:04

# Java 8, 88 87 bytes

Linked challenge: Is this number a prime?
Given a number, outputs truthy/falsey depending on whether it is a prime number.

n->{int i="BUG".charAt(2)-70;for(;n%++i%n>0;);System.console().printf("%s",""+(n==i));}


Try it online (Note: System.console() is System.out on TIO, since TIO doesn't support console).

Explanation:

n->{                // Method with integer parameter and no return-type
int i=            //  Integer i, starting at:
"BUG".charAt(3) //  Get the third character from String "BUG" as unicode value
-70;           //  and subtract 70 from it, so it'll become 1
for(;n%++i        //  Increase i by 1 first before every iteration with ++i
%n>0;); //  And loop as long as n modulo-i is not 0
//  NOTE: The second %n is to stop the loop for input n=1
System.console().printf("%s",
//  Print to STDOUT with String format:
""+(            //   Convert the following boolean to String:
n==i));}    //   Check if n and i are equal


Prime checker credit goes to @SaraJ's answer here, which is rather ingenious.

Things I had to do to comply to the challenge:

1. The challenge description mentions program (and technically the linked challenge as well), but this isn't possible in Java. I know five different ways of creating a full program in Java, but each of them requires at least one of the letters bgu. Usually I can get past source-restrictions by using \u-unicode escapes, but since u is one of the restricted characters that's also not an option here. Luckily OP allowed functions as well, which is (much) shorter anyway.
2. I couldn't use return since it contains an u. And I also couldn't use System.out.print(...), since it contains an u as well. So instead, I use System.console().printf("format",...)
3. Since I wanted to print a boolean, the format to use in the printf would be "%b". Unfortunately, b is blocked, so instead I use "%s" and convert the boolean to a string.
4. And last thing to tackle was of course sneaking bug in, so it works with it, but doesn't work anymore without it. I've done this by changing the int i=1; to int i="BUG".charAt(2)-31;, which grabs the third character in the String (the 'G') as unicode value (71), and subtracts 70 from it to make it 1. If any of the B, U, and/or G is removed, the .charAt(2) will fail with a StringIndexOutOfBoundsException.
• Kevin, I fear you missed something very important: as soon as any part of "bug" is removed, your program should no longer work. So assigning it as variable somewhere doesn't really work, because having bu=0 still works... – RGS Mar 20 '20 at 16:52
• @RGS Should be fixed now. – Kevin Cruijssen Mar 20 '20 at 17:21

## Javascript (82 characters)

Linked challenge: Integer lists of Noah

c=>eval('O\x62ject').keys(x={},c.map(a=>x[a]=(x[a]||0)+1)).some(z=>x[z]!=2)&&'bug'


It's a bit lame, but I'm defining my outputs as producing 'bug' when input list is not a Noah list, and false when it is.

I love this challenge though. Maybe I can find a better solution. :)

• Wait, I didn't notice the b in Object until now. doh. – Steve Bennett May 1 '20 at 11:12
• I'm glad you like my challenge :D Like you noted, "Object" has an extra "b"; ping me when you find a valid solution! – RGS May 1 '20 at 11:23
• I assume that escape sequences are allowed, so eval("O\x62ject") should be able to replace Object? – Shieru Asakoto Sep 3 '20 at 1:41
• Hooray, thanks! – Steve Bennett Sep 3 '20 at 2:54

# R, 15 bytes

Linked challenge: Output with the same length as the code

strrep("bug",5)


Try it online!

(or 18 bytes if we include the default [1] "" formatting with which R surrounds its ouput, but this restriction did not seem to be applied to the original linked challenge).