Questions tagged [quine]

A quine is a program which produces its source as output. This tag indicates that the challenge is related to quines.

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227
votes
406answers
56k views

Golf you a quine for great good!

Using your language of choice, golf a quine. A quine is a non-empty computer program which takes no input and produces a copy of its own source code as its only output. No cheating -- that means ...
39
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17answers
4k views

Golf a mutual quine

Using two languages of your choice, write the smallest “mutual quine” you can. That is, write a program P in language A that outputs the source code for a program Q in language B, such ...
64
votes
43answers
5k views

Write the shortest self-identifying program (a quine variant)

Write a program that will generate a "true" output iff the input matches the source code of the program, and which generates a "false" output iff the input does not match the source code of the ...
85
votes
69answers
15k views

Print your code backwards - reverse quine

Write a program that prints its own source code out backwards, in other words an eniuq. Scoring: +50 if you use pull data from the Internet. +25 if you read your own source code. +1 point per ...
117
votes
56answers
37k views

Program that creates larger versions of itself (quine-variant)

You are to write a program that will output source code that is Larger than the original program (character wise) Will print another program larger than itself when run (i.e. the new program is also ...
118
votes
112answers
15k views

Make an error quine!

Your challenge: write a "program", for a language of your choice, that causes the compiler/interpreter/runtime to produce error output when compiling/running your program which is identical to your ...
36
votes
20answers
4k views

Write a Polyquine

A polyquine is both quine and polyglot.1 You are to write a quine which is valid in at least two different languages. This is code golf, so the shortest answer (in bytes) wins. 1 I made that up. Or ...
29
votes
4answers
2k views

Create a rotating quine

A rotation of a string is made by splitting a string into two pieces and reversing their order, for example "world!Hello, " is a rotation of ...
40
votes
3answers
5k views

Radiation Hardened Quine

As you should (hopefully) know, a radiation hardened quine is a quine that you can remove any one character from and still print its original, pre-modified source. The thing is, with most of these you ...
35
votes
6answers
1k views

Mutually Exclusive Quines

Your challenge is simple. Write two programs that share no characters which output each other. Example Two programs P and Q are mutually exclusive quines if: P outputs Q Q outputs P There is no ...
17
votes
3answers
992 views

Write a third order quine

This challenge is an extension of 'Golf a mutual quine'. Using three languages of your choice, create a third order Ouroboros program. That is, in language A, write a program pA which outputs ...
103
votes
30answers
15k views

Print a Negative of your Code

Consider a square of printable ASCII characters (code points 0x20 to 0x7E) for side length N, like the following (here, N = 6): ...
46
votes
1answer
1k views

Cyclic Levenquine

Background As most PPCG regulars will know, a quine is a program which outputs its own source code when run; and the Levenshtein distance between two strings is the minimum number of insertions, ...
74
votes
46answers
6k views

Input ∩ Source Code

Intro The challenge is to create a program/function that prints the intersection of its own source code and a given string input. This is code golf and to be more precise: Let ...
45
votes
15answers
2k views

Stack Exchange Vote Counter

Write a program/function that returns the vote count of its own Stack Exchange answer at the time of its execution. Your program/function may access this page (codegolf.stackexchange.com/questions/...
28
votes
6answers
2k views

Can you Meta Quine?

Similar to other quine puzzles (more specifically, this one), write a program that produces the source for itself. Here's the new twist: The code produced should NOT be identical to the source. ...
22
votes
4answers
1k views

Cryptographic quine variant

Create a program that prints the MD5 sum of its source in the form: MD5 sum of my source is: xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx No cheating - you can't just read ...
21
votes
7answers
965 views

Generate Programs in Increasing size

In this challenge, you will write a program which outputs a program which is the double the length of the original program. The outputted program should output a new program a program double its ...
14
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9answers
1k views

Character counts in source code

Write a program that outputs a list of the number of occurrences of each unique character in its source code. For example, this hypothetical program ...
37
votes
8answers
2k views

Mirror quine (or my head hurts)

I was reading Print your code backwards - reverse quine And I thought, this could be more interesting if your backwards code is also executable. So this challenge will have all the rules and ...
24
votes
2answers
760 views

Rotation-safe quine

Write a proper quine whose every rotation is itself a proper quine. For example, if your source code is abcdef, then: abcdef ...
31
votes
21answers
4k views

Interquine - Two programs that output each other in a loop

Program A outputs program B's code when run, and B outputs A's source. Requirements: Only one language across both programs Programs are different. One program that outputs itself does not qualify. ...
45
votes
26answers
3k views

Output the first position in your program for each input character

Challenge Write a non-empty program/function p that, given a non-empty input string s, outputs the position of the first ...
12
votes
15answers
2k views

Quine outputs itself in binary

Your task, if you wish to accept it, is to write a program that outputs its own source code in the binary UTF-8 representation. Rules The source must be at least 1 byte long. Your program must not ...
10
votes
5answers
1k views

It's Anagram Quine, not just Quine!

The Task In this challenge, your task is to write a program, which takes in no input, with as many anagrams that are quine of themselves as possible. Your score will be the number of anagrams of your ...
10
votes
11answers
2k views

Tri-interquine - Three programs that output each other in a loop

Related: Interquine Program A outputs program B's code when run, and B outputs C's source, and C outputs A's source. This time you can't exchange two characters and exchange again :) Requirements: ...
46
votes
3answers
5k views

Code that runs the Game of Life on itself

Write two rectangular blocks of code, each w characters wide and h characters tall, that implement Conway's Game of Life when arranged in a grid. (w and h may be any positive integers) For example, ...
36
votes
6answers
3k views

Make the largest infinity that you can!

The ordinal number system is a system with infinite numbers. A lot of infinite numbers. So many infinite numbers that it literally does not have an infinity to represent its own infiniteness. The ...
72
votes
29answers
6k views

2016 Time Capsule String: How Versatile Is Your Language?

About a year ago on Dec 31, 2015, I had the idea that: We should make a time capsule string. Everybody gets to add one character and next new years we'll see who can make the best program out of all ...
64
votes
73answers
9k views

A "cheating" quine

Long-time lurker, first-time poster. So here goes. In the Wikipedia page for quine, it says that "a quine is considered to be 'cheating' if it looks at its own source code." Your task is to make one ...
42
votes
10answers
5k views

Write a Quine in Plain English

Write a quine that consists of real English words separated by single spaces. A "word" is defined as a string containing only lowercase and uppercase letters (...
41
votes
9answers
2k views

Make a slow error quine maker!

As part of his answer to Make an Error Quine!, @Falko proposed the following algorithm: How to create your own solution in 2 minutes? Open a new file in an IDE of your choice. Bang your ...
32
votes
7answers
3k views

Tips for writing quines

A quine is a program that produces output that's identical to the program's source code. On this website, we generally only care about proper quines (at the time of writing, the current definition is "...
31
votes
7answers
2k views

Three polyglots, two period-two quines, and one code-golf challenge

Produce a program A such that running it in language A produces Program B, and running program A in language B produces program C. Program B, when run in language B produces Program A, and running ...
44
votes
29answers
5k views

Self-growing code codee codeee codeeee

Write a program (or function) (let's call it P1), that when run, outputs another program P2 of the same language and exactly 1 byte longer than P1. Program P2 when run, should output a 3rd program P3 ...
27
votes
18answers
17k views

Create a "hacker typer" program that renders its own source code

If you are unfamiliar with hacker typer, see hackertyper.net. In short, it is a program that outputs one chunk of a code base per keystroke for comedic effect. BUT, the hackertyper.net version is far ...
21
votes
32answers
3k views

Print out the first N characters of your code

You should write a program or function that receives a positive integer N as input and prints out the first N characters of your ...
15
votes
1answer
1k views

How long is your (language) snake?

Following on from the third order quine challenge, your task is to write an Ouroboros program that uses as many languages as possible. That is, in language A, write a program pA which outputs program ...
30
votes
30answers
2k views

A Quine on Every Line

Your goal is to create a program that prints itself indefinitely, with a new line after each one. Thus, if your program is a one-liner, it would be repeated on every line of the output. Example ...
23
votes
25answers
2k views

Quine Anagrams! (Cops' Thread)

This is the cops' thread. For the robbers' thread, click here. Cops' Task First, write a quine in a language of your choosing. Next, scramble the quine. Make sure to do this well as the robbers will ...
19
votes
9answers
1k views

Fibonacci program lengths

Write a program with length n that outputs another program whose length is the next Fibonacci number after n. The new program must do the same thing - output another program whose length is the next ...
18
votes
24answers
2k views

Counting characters

Write a function or program that accepts one character (or a string of length 1) as input, and outputs the number of times that character occurs inside the code. This program must be a Proper Quine, ...
40
votes
2answers
1k views

Radiation softened quine

It's simple: Make a proper quine where if you remove any character, it's still a quine. The difference between this and a radiation hardened quine is that if your program is ...
27
votes
7answers
2k views

Mutual Negative Quines

This was inspired by Print a Negative of your Code and Golf a mutual quine. Consider a rectangle of characters, that meet the following restrictions: Consists solely of printable ASCII characters ...
27
votes
12answers
2k views

Quine / Reverse Quine

Write a complete program that takes a boolean or non-negative integer input. It must: Output its own source code if the input value is falsy Output its own source code in reverse if the input value ...
22
votes
11answers
2k views

Narcissistic Quine [duplicate]

Write a program/method that: Becomes a quine when the input matches the source code; Doesn't halt otherwise. This is code-golf, so shortest solution wins. Avoid any standard loopholes.
20
votes
7answers
745 views

Generate a Markdown Template for your Post

Your task is simple: Write a program (or function) that takes no input and outputs something like this: ## *name*, *length* bytes *code* Where ...
16
votes
19answers
1k views

Generate programs that print n times their length

Given a nonnegative integer n, your solution must output a program in your chosen language whose output has n times as many ...
12
votes
9answers
1k views

The longest period iterating quine

As we know, a quine is a program that outputs its own source code. However, it's also possible to write a program that outputs another, different program, that outputs the first program again. For ...
8
votes
14answers
818 views

Quine Anagrams! (Robbers' Thread)

This is the robbers' thread. For the cops' thread, click here. Cops' Task For the cops' thread, click here. Robbers' Task Find an uncracked submission on the cops' thread. (A submission may only be ...