Questions tagged [string]

A competition to solve a particular problem through the usage and manipulation of strings.

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505 votes
932 answers

"Hello, World!"

So... uh... this is a bit embarrassing. But we don't have a plain "Hello, World!" challenge yet (despite having 35 variants tagged with hello-world, and counting). While this is not the most ...
184 votes
386 answers

1, 2, Fizz, 4, Buzz

Introduction In our recent effort to collect catalogues of shortest solutions for standard programming exercises, here is PPCG's first ever vanilla FizzBuzz challenge. If you wish to see other ...
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103 votes
315 answers

Simple cat program

One of the most common standard tasks (especially when showcasing esoteric programming languages) is to implement a "cat program": read all of STDIN and print it to STDOUT. While this is named after ...
52 votes
6 answers

Language Design: 2-D Pattern Matching

This is Fortnightly Challenge #6. Theme: Language Design There's a chatroom for this challenge. Come and join us if you want to discuss ideas! And now for something completely different... This ...
  • 28.6k
91 votes
165 answers

"99 Bottles of Beer"

Write a program that outputs the lyrics to 99 Bottles of Beer, in as few bytes as possible. Lyrics: ...
  • 7,404
89 votes
154 answers

Determine whether strings are anagrams

Challenge Given two strings, work out if they both have exactly the same characters in them. Example Input word, wrdo This returns true because they are the ...
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30 votes
8 answers

crossed out 44 is still regular 44 ;(

Introduction On March 24th, 2015 @isaacg golfed his Pyth answer from 44 to 42 bytes. Since a crossed out 44 (44) looks a lot like a regular 44, @Optimizer made the following comment: striked out ...
60 votes
43 answers

Are the brackets fully matched?

You must write a program or function that takes a string of brackets and outputs whether or not that string is fully matched. Your program should print a truthy or falsy value, and IO can be in any ...
  • 57.4k
31 votes
29 answers

Say What You See

The "Look and say" or "Say what you see" sequence is a series of numbers where each describes the last. ...
  • 441
64 votes
124 answers

Reverse stdin and place on stdout

Requirements: Take an input on stdin including new lines / carriage returns of unlimited length (only bounded by system memory; that is, there is no inherent limit in the program.) Output the reverse ...
  • 3,272
91 votes
170 answers

Print a Tabula Recta!

The Tabula Recta (sometimes called a 'Vigenere Table'), was created by Johannes Trithemius, and has been used in several ciphers, including all variants of Bellaso's Vigenere cipher and the Trithemius ...
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44 votes
23 answers

Levenshtein Distance

While there are many edit distance questions, such as this one, there isn't a simple question to write a program that calculates the Levenshtein distance. Some Exposition The Levenshtein edit ...
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16 votes
9 answers

Base Conversion With Strings

Introduction We've have a few base conversion challenges here in the past, but not many designed to tackle arbitrary length numbers (that is to say, numbers that are long enough that they overflow the ...
  • 3,548
27 votes
66 answers

Is string X a subsequence of string Y?

Given strings X and Y, determine whether X is a subsequence of Y. The empty string is regarded as a subsequence of every string. (E.g., '' and ...
  • 3,042
88 votes
228 answers

"DDoouubbllee ssppeeaakk!!"

Super simple challenge today, or is it? I feel like we've heard a fair bit about double speak recently, well let's define it in a codable way... Double speak is when each and every character in a ...
  • 11.3k
38 votes
53 answers


Related but very different. A boustrophedon is a text where every other line of writing is flipped or reversed, with reversed letters. In this challenge, we will just reverse every other line, but ...
  • 28.3k
29 votes
12 answers

Word Search Puzzle

Given a rectangular text as a word search puzzle and a search string, determine if the text contains the search string. The search string may appear: horizontally, vertically or diagonally forwards ...
20 votes
50 answers

Run Length Decoding

Write the shortest code in the language of your choice to perform run length decoding of the given string. The string will be supplied as input on stdin in the form ...
  • 1,285
127 votes
200 answers

Sing Happy Birthday to your favourite programming language

Your favourite programming language has just had a birthday. Be nice and sing it the Happy Birthday song. Of course you should accomplish this by writing a program in that language. The program takes ...
  • 2,021
44 votes
21 answers

One Ring to rule them all. One String to contain them all

Objectives: Output a String which contains every positive integer strictly below 1000. The obvious answer would be to concatenate every one of them, and that would create a String of 2890 characters (...
  • 633
16 votes
33 answers

Spell out the Revu'a

Actually not inspired neither by Atbash Self Palindromes nor by Generalized Gematria Calculator. Given a string s of length n, output the Revu'a sequence, which is the first character of s, the first ...
  • 28.3k
26 votes
23 answers

Case Permutation

Who needs to compare things case insensitively when you're able to generate every permutation of uppercase and lowercase? No one! That's the answer. No one does. Your task is to achieve this feat; ...
  • 3,145
182 votes
29 answers

Do you want to code a snowman?

Here is a simple ASCII art snowman: _===_ (.,.) ( : ) ( : ) Let's make him some friends. This will be the general pattern for our ASCII art snowpeople: ...
22 votes
54 answers

Display number of occurrences for every character in an input string

The code should take a string as input from keyboard: The definition of insanity is quoting the same phrase again and again and not expect despair. The output ...
45 votes
139 answers

Full Width Text

Full width text is text that has a space after every character, including the last one. For instance, the first sentence of this question becomes: ...
18 votes
54 answers

Find the occurrences of a character in an input string

Challenge Write a program that, given a string x which is 10 characters long and a character y, outputs the number of times ...
72 votes
155 answers

Print X without X (cop's thread)

This is the cop's thread of a cops-and-robbers challenge. You can view the robber's thread here A pretty common beginner style question is to print some string, but there's a catch! You need to do it ...
  • 90.1k
52 votes
49 answers

Outputting ordinal numbers (1st, 2nd, 3rd)

I would like to generate (as a return result of a function, or simply as the output of a program) the ordinal suffix of a positive integer concatenated to the number. Samples: ...
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13 votes
6 answers

Text to Brain-Flak

Your challenge is to turn input text to brain-flak code that will output the text. Tutorial taken from here with permission here Brain-Flak has two stacks, known as 'left' and 'right'. The active ...
  • 3,522
53 votes
11 answers

Unfolding the Hexagony source code

Introduction If you're not familiar with Hexagony, it's an esoteric language created by Martin Büttner. The thing is that this language accepts multiple forms for the program. The following programs ...
  • 43.5k
31 votes
27 answers

Palindromizing the strings

Introduction For the ones who don't know, a palindrome is when a string is equal to the string backwards (with exception to interpunction, spaces, etc.). An example of a palindrome is: ...
  • 43.5k
63 votes
43 answers

User Appreciation Challenge #1: Dennis ♦

I got the spontaneous idea of making a series of challenges of users that have helped and continue to help the PPCG community be an enjoyable place for everyone, or maybe just specifically for me. :P ...
  • 40.3k
46 votes
10 answers

Zigzagify a String

Write a program (or function) that takes in a non-empty string of any printable ASCII characters. Print (or return) a zigzagging chain of the characters in the string with every neighboring pair of ...
28 votes
46 answers

Transpose a page of text

EDIT I modified the wording of the rules to make some things which were implicit more explicit. I also added some emphasis to clear up some points of apparent confusion, and explicitly defined the ...
46 votes
79 answers

Type uniqchars!

Given a string consisting of printable ASCII chars, produce an output consisting of its unique chars in the original order. In other words, the output is the same as the input except that a char is ...
  • 100k
26 votes
19 answers

Coding Convention Conversion

In that Coding Golf, you should convert one coding convention with TitleCase to lower_case_with_underscores. And... vice versa! Specification Change the casing in a following way: If underscore ...
25 votes
42 answers

Surround a string with hashes

I've already made this in Python, but it seems that it could be shortened a lot: ...
  • 361
22 votes
2 answers

Each step of the Levenshtein distance

In this challenge you will write a program that takes two newline-separated strings, s1 (the first line) and s2 (the second line), as input (STDIN or closest). You can assume that the length of s1 ...
  • 8,050
10 votes
10 answers

Split string into n pieces (or pieces of length n)

The Challenge In this challenge you have to do two different (but related) tasks depending of the order of the input. Your program will recieve a string s and an ...
  • 6,791
-6 votes
13 answers

Substitution cipher [duplicate]

A substitution cipher is an encoding method where each letter in the alphabet is replaced with a fixed, different one; for example, given the following substitution map: ...
  • 147
390 votes
47 answers

Covfefify a string

In this challenge, you must take a string matching the regex ^[a-zA-Z]+$ or whatever is reasonable (you don't have to consider uppercase or lowercase letters if you ...
165 votes
128 answers

Trick or Treat polyglot

Since Halloween is coming up I thought I might start a fun little code golf challenge! The challenge is quite simple. You have to write a program that outputs either ...
  • 1,531
95 votes
34 answers

Would this string work as string?

Write a program that takes a single line string that you can assume will only contain the characters /\_‾. (That's forward and backward slash, underline and ...
53 votes
94 answers

Is it double speak?

In an earlier challenge I asked code golfers to produce strings which copy each character in a string. For example: TThhiiss iiss ddoouubbllee ssppeeaakk!! This ...
  • 11.3k
21 votes
9 answers

Generating PBM bitmap files from ASCII text

The PBM (Portable BitMap) format is a very simple ASCII black and white bitmap format. Here's an example for the letter 'J' (copy-pasted from the wikipedia link): P1 # This is an example bitmap of ...
  • 1,659
42 votes
16 answers


UPDATE : isaacg's Pyth submission is the winner! Many of you must have heard that there is a cooler version of JavaScript in town (read ES6) which has a method ...
  • 26.3k
31 votes
30 answers

Is it a Bumpy Word?

(inspired by this challenge over on Puzzling -- SPOILERS for that puzzle are below, so stop reading here if you want to solve that puzzle on your own!) If a letter in a word occurs alphabetically ...
  • 42.9k
27 votes
39 answers

I reverse the source code, you reverse the input!

Yet another blatant rip-off of a rip-off of a rip-off. Go upvote those! Your task, if you wish to accept it, is to write a program/function that outputs/returns its string input/argument. The tricky ...
  • 5,877
39 votes
53 answers

Generate the Abacaba sequence

This challenge is about printing the abacaba sequence of a specific depth. Here is a diagram of the first 5 sequences (a(N) is the abacaba sequence of depth N, ...
  • 8,050
33 votes
63 answers

"Multiply" two strings

This was inspired by a function I recently added to my language Add++. Therefore I will submit an short answer in Add++ but I won't accept it if it wins (it wouldn't be fair) Don't you hate it when ...

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