101 questions linked to/from Default for Code Golf: Input/Output methods
Is a regex answer valid if it gives the reciprocal of the required output? [duplicate]
This answer gives the reciprocal of the required output, rather than the required output itself. In a simpler challenge this might cut out a significant part of the work, but for this particular ...
Is outputting a Maybe acceptable in Haskell? [duplicate]
The vote on this output option has moved here. Haskell has a very strong type system, so there is a type called Maybe to work around some restrictions. The ...
What input methods should we allow for Code Golfs? [duplicate]
Should we define rules on how input can be fed into programs? This question on SO allowed for any input method, which resulted in answers which ripped off the question by doing the computation in ...
For Code Golf, how do you deal with languages without a traditional print/echo statements? [duplicate]
Returning a function, which returns the result? [duplicate]
Submission formats are always flexible here on PPCG. Named functions, anonymous functions or even full programs that perform IO, are all fine. Even currying is acceptable, for example, taking ...
JS Promises in code-golf? [duplicate]
Should code-golf submissions written in JS that return a promise be allowed? For example: Promise.resolve("hi") Doesn't output ...
Should the output to STDERR count as output length? [duplicate]
A few challenges that requires the program to output something at a specified length, and a bunch of answers well... uses built-in error messages that's generated by the interpreter rather than the ...
Is Ans considered a valid form of input for TI-BASIC? [duplicate]
We haven't reached a complete consensus on whether or not Ans is permitted as a valid input format for TI-BASIC. We have this answer on "Default for Code Golf: ...
What counts as "output" in SQL? [duplicate]
Some of the site's questions rule that something must (or must not) be printed to the output. My question is, in the case of SQL, what really is the output? The ...
Hard coding input [duplicate]
I've seen some answers that hard code the input or rely on the existence of a user-defined variable, see for example this question. The OP asked for a "function or equivalent subprogram". I don't ...
Why can't we take input from a variable? [duplicate]
On the default allowed I/O methods, we have come to a consensus that programs may not take input from a predefined variable. However, we have decided that anonymous functions are allowed. In the ...
When accepting input from STDIN, can it be assumed to terminate with a newline [duplicate]
...or I guess more specifically, can I require that input from STDIN (or closest alternative, e.g. TIO) be newline terminated? Utilising apps like TIO this isn't added, but if using a terminal with <...
What's a number? [duplicate]
Similar to What's a string? If a challenge says that the input will be “a number”, what data types are acceptable? Obviously, types like int and ...
Do programs need to take input, if it is in the spec? [duplicate]
Recently, there have been some challenges involving the OEIS. Specifically, when given an index as input, the challenge spec involves output the item in the OEIS at that index. However, for constant ...
Is it acceptable to take input in two different formats? [duplicate]
This isn't an issue yet, but I could see it become one sometime soon. Can I take input in two, or even more, separate formats, provided they're both reasonable formats? For example, let's say one ...
In code-golf is it always ok to print ASCII digits when an integer is asked for? [duplicate]
When the question clearly asks for an integer is it always OK to just print the ASCII digits of the integer without actually generating the integer value? The consensus is yes. It's the programs/...
Clarification of global variables as "arguments" [duplicate]
Say language X supports functions, but input must be done through one of the predefined global variables (all initialized to zero). Can I consider this a use of an argument? Similarly can I use this ...
Sandbox for Proposed Challenges
This "sandbox" is a place where Code Golf users can get feedback on prospective challenges they wish to post to main. This is useful because writing a clear and fully specified challenge on ...
Loopholes that are forbidden by default
There are a number of standard loopholes which experienced question-setters seek to explicitly close. However, inexperienced question-setters may unintentionally leave them open, or respondents may ...
Things to avoid when writing challenges
If there is something that you find annoying / counterproductive / unfair / detrimental / no longer funny in challenges (question posts), describe it in an answer here, and propose a recommended ...
New users' guides to golfing rules in specific languages
What are the most important rules a first-time golfer in a given language should know? For instance, how do golfed programs usually take input and output? Each language should have a single CW answer ...
Default for Code Golf: Program, Function or Snippet?
One of the things many (new?) users forget to specify in code-golf challenges is whether the answers should provide a full program or a function (or even just a snippet). For most such things, we have ...
Default acceptable image I/O methods for image related challenges
I do not feel that the default general acceptable I/O methods sufficiently cover image-processing and graphical-output challenges. So I would like to poll. What are the default acceptable I/O methods ...
Standard definitions of terms within specifications
Quite often I find that I am repeating myself when creating a challenge. For example, usually I have to retype the definition of "random" in all of my posts, or I have to specify the same thing about ...
Can numeric input/output be in unary?
Some string-based languages (including but not limited to sed, Retina, ///) can't really handle integer arithmetic in decimal (or other normal bases). Therefore, these almost always have to start by ...
Best of CGCC 2022 - Voting Now Open!
Final phase You have chosen the categories and the nominees for CGCC's annual "Best of". Now it is time to pick the winners! Each of the 16 categories is represented by an answer to this ...
Things to consider when creating a challenge
There's a lot to remember to include when writing a challenge for this site. What are some things that are easy to forget? Return to FAQ index
Command-line flags on front ends
Our standard policy regarding command-line flags states that one should count the space before the dash (-) too, when there aren't any "free" options, since it ...
Welcome to Code Golf and Coding Challenges Stack Exchange!
What is this site? This is a place to host recreational coding challenges, such as code golf. We are unlike most sites in the Stack Exchange network. We are not a question-answer site, nor are we a ...
What's a string?
If a challenge says that input will be in the form of a string, what is acceptable? Various languages have different ways of implementing strings, so here's what I've "borrowed" from Wikipedia: ...
How does this site work?
Hello, I have spent time looking at the StackExchange sites and especially this has seemed quite interesting to me. But I would like you to explain how it works and what it is about. I know how to ...
Default policy for output in decision problems
Challenges tagged as decision-problem involve "deciding whether the input meets certain criteria". Although some challenges with this tag involve more than two categories, most involve only ...
Why are some users so quick to jump on a bandwagon?
I've been lurking on this site long before I made my account, and I've seen many cases where people are downvoted simply because they post an answer in the same language as someone else and it happens ...
Should submissions be allowed to exit with an error?
Suppose we have the following Python code: f=lambda x:x*2 X The first line defines a function which doubles a number. Then the second line is reached, is found ...
Do function submissions have to be reusable?
Simple question: if I answer a code golf with a function (for a task which is supposed to terminate), does the function actually have to be reusable? Or could it, say, modify some globals which break ...
While to-be-posted challenges get feedback in the Sandbox (ideally), we don't usually reflect on challenges after they have run. And while issues and ambiguities in challenges do get pointed out, we ...
When to allow flexible input/output
First, I hope this isn't a duplicate (I've tried my best to search through for similar questions, but I very well may have overlooked one). In the spirit of being fair to inflexible programming ...
List input in C and length argument
When dealing with list input in C, as in this question, is it acceptable to add extra argument to indicate the length of the list? It does give advantages because other language needs functions like <...
New First-Time Asker Dialog
This revision has been submitted to the devs to push the change, so unless there are any critical issues, this is the final version and I will not be modifying it anymore. (I have cut down the post ...
Should we disallow non-observable requirements?
One of the more recent things to avoid that's coming up a lot is the use of non-observable requirements. The most common incarnations of this are things like "no hardcoding", "implement this algorithm"...
Is the empty string an acceptable decimal representation of 0?
In a recent question for which the correct output for 1 is zero, an answer output ; i.e, nothing. Is this an acceptable base-10 ...
What details should always be given for a code golf task?
Related: For Code Golf, how do you deal with languages without a traditional print/echo statements? Related: What programming language should we consider for the code-golf solution ? Related: Use of ...
Can numeric input/output be in the form of byte values?
This answer just prompted a question, which I've wondered about a few times when answering challenges in esoteric languages: For some esoteric languages, the only means of input/output is reading and ...
Should the standard loophole meta thread have the featured tag?
Almost all of our challenges on PPCG have the implied rule of no standard loopholes. However, I have seen many answers (mainly from new users) that contain some of these standard loopholes. Should we ...
Is this an acceptable way to shave a byte in ES6?
Say there's a challenge with two inputs. Can we submit a function signature like this? a=>b=>... Instead of ...
What even is a "function" by our standards?
On a recent question, the following was brought up by @Sp3000: In fact, I'm almost starting to wonder what a "function" is, since it seems like every language with goto could define a "function" ...
Should we start "reviving" older challenges?
Related. Earlier today, AdmBorkBork posted this question on TNB, asking whether or not PPCG was dying. In the following discussion, I have suggested we, as a community, could start "reviving" (for ...
Does Baba Is You belong here?
Introduction Baba Is You is a puzzle game. In this game, a level is a grid that consists of objects and texts, and the objective of the level is to, if there are texts ...
Can a Prolog predicate have multiple choice points if it always chooses the correct solution first?
This stems from JoKing's answer to Sums of Consecutive Integers, where it can be seen that the predicate always unifies Z with the correct answer first. However, ...
CGCC Blog Post #2: The history of PPCG and CGCC
We recently turned 10 years old. Unfortunately, we didn't really realise and therefore didn't really celebrate or even mark the occasion. But, it got me thinking about the history of the site, and now ...