• Answers will occasionally be moved to the Sandbox archive when there are too many of them. When using them to report bugs, keep an eye on the post.
  • This site, Meta Stack Exchange, is usually used as a "test bed" for pending changes happening to the way text is rendered on all network sites. Changes to text rendering that are going to be rolled out to the network are usually deployed here first to test them out and fix any potential glitches. Currently, there are no such changes pending, but if there were, keep in mind that text posted here may render differently from the other sites until the changes roll out to them as well.

As per Jeff's suggestion in this comment:

You can use this question as a formatting sandbox. You can:

  • edit this question itself (Community Wiki questions such as this one require only 100 reputation to edit instead of 2,000)
  • post answers to this question (This question might be protected, requiring earning 10 reputation on this site to answer)
  • post comments to this question or its answers
  • test suspected bugs with the editor or the rendering
  • post ponies (only when mods are asleep)

Beware that since the changes to syntax highlighting in December 2010, and the inline hints added in March 2011, no syntax highlighting is applied unless the question's tags or an inline hint enable it. So, to test highlighting here in the sandbox:

  1. As of January 8, 2019, you can use GitHub-flavor fenced code blocks in your posts, specifying the language after the opening fence:

    While not hinted otherwise: <html></html> source <b>goes</b> "here".
    var a = 3;
    while (not (a > 0)) {
        alert("JavaScript code <b>goes</b> here.");
  2. Or:

    • Create code blocks in any way (using the fence notation above, the four-space indent form, or using HTML <pre><code> tags).

    • Save your post.

    • Use your browser's developer tools to edit the resulting HTML. To open developer tools, press F12, or ⌥⌘ I on Mac.

    • Find the <pre> element and add the attribute class="prettyprint", or change it into one of the valid syntax hints linked above, like class="lang-vb prettyprint".

    • Run the following in the location bar: javascript:prettyPrint(); or prettyPrint() in the console.

Answers that are considered annoying or obnoxious, or that cause breakage for users, will be deleted. This is codified as a policy as of March 29, 2018.

  • Bold code block.Italic code block. – smileycreations15 Mar 4 '19 at 12:36
  • Is new line working correct? Adding two spaces at the end of this line And now the new line... And another another... No new lines :( – smajli Mar 5 '19 at 11:14
  • New line </br> continue in new line... – smajli Mar 5 '19 at 11:16
  • Test: meta.stackexchange.com/questions/324682/… – Alex Mar 17 '19 at 2:35
  • Do HTML &quot; entities &quot; work&nbsp;? Guess not. – a vaccinating arachnid Apr 1 '19 at 22:18
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    A comment with some weird markdown, to test and help this user. Look tags work too, and so does tour. – Bhargav Rao Apr 6 '19 at 1:59
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    Note: Do not remove @BhargavRao's comment, or you will break this answer – wizzwizz4 Apr 6 '19 at 17:16
  • @BhargavRao When sandbox answers are moved to the archive, comments such as this one -- on the question itself -- aren't migrated; they're deleted. – rgettman Apr 9 '19 at 19:37
  • @rgettman, yeah, that is fine. I had used it for just a small demonstration. The linked answer itself is self-sufficient. Thanks anyway. – Bhargav Rao Apr 9 '19 at 20:22
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    ‮‮‮‮‮‮‮‮‮‮‮‮‮‮‮‮‮‭‬‭‭‬ ‭‮‬‬ ‬‮‮‮‮‮‮‮‮‮‮‮‮‮‮‮‮‮‭‬‭‭‬ ‭‮‬‬ ‬‮‮‮‮‮‮‮‮‮‮‮‮‮‮‮‮‮‭‬‭‭‬ ‭‮‬‬ ‬‮‮‮‮‮‮‮‮‮‮‮‮‮‮‮‮‮‭‬‭‭‬ ‭‮‬‬ ‬‮‮‮‮‮‮‮‮‮‮‮‮‮‮‮‮‮‭‬‭‭‬ ‭‮‬‬ ‬‮‮‮‮‮‮‮‮‮‮‮‮‮‮‮‮‮‭‬‭‭‬ ‭‮‬‬ ‬‮‮‮‮‮‮‮‮‮‮‮‮‮‮‮‮‮‭‬‭‭‬ ‭‮‬‬ ‬‮‮‮‮‮‮‮‮‮‮‮‮‮‮‮‮‮‭‬‭‭‬ ‭‮‬‬ ‬‬‭‮‮‮‮‮‮‮‮‮‮‮‮‮‮‮‮‮‭‬‭‭‬ ‭‮‬‬ ‬‬‭‮ Such an odd comment...‮‮‮‮‮‮‮‮‮‮‮‮‮‮‮‮‮‭‬‭‭‬ ‭‮‬‬ ‬‬‭‮‬ – mindstormsboi Jun 18 '20 at 1:16
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    ‮sdrawkcab si tnemmoc sihT – Donald Duck Jul 4 '20 at 1:03
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    SOBotics Tool to get the source text of this comment. Single backslash and single backtick: \, `. Type: ``\``, `\``. – Sebastian Simon Jul 12 '20 at 23:23
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    Note: Do not remove @wizzwizz4's comment, or you will not know that you don't have to delete Bhargav Rao's comment. – Big Brother Jul 18 '20 at 11:49
  • 1
    ‮‮‮‮‮‮‮‮‮‮‮‮‮‮‮‮‮‭‬‭‭‬ ‭‮‬‬ ‬‮‮‮‮‮‮‮‮‮‮‮‮‮‮‮‮‮‭‬‭‭‬ ‭‮‬‬ ‬‮‮‮‮‮‮‮‮‮‮‮‮‮‮‮‮‮‭‬‭‭‬ ‭‮‬‬ ‬‮‮‮‮‮‮‮‮‮‮‮‮‮‮‮‮‮‭‬‭‭‬ ‭‮‬‬ ‬‮‮‮‮‮‮‮‮‮‮‮‮‮‮‮‮‮‭‬‭‭‬ ‭‮‬‬ ‬‮‮‮‮‮‮‮‮‮‮‮‮‮‮‮‮‮‭‬‭‭‬ ‭‮‬‬ ‬‮‮‮‮‮‮‮‮‮‮‮‮‮‮‮‮‮‭‬‭‭‬ ‭‮‬‬ ‬‮‮‮‮‮‮‮‮‮‮‮‮‮‮‮‮‮‭‬‭‭‬ ‭‮‬‬ ‬‬‭‮‮‮‮‮‮‮‮‮‮‮‮‮‮‮‮‮‭‬‭‭‬ ‭‮‬‬ ‬‬‭backward comment‮‮‮‮‮‮‮‮‮‮‮‮‮‮‮‮‮‭‬‭‭‬ ‭‮‬‬ – ppwater Nov 30 '20 at 1:32
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    @ppwater pasting the contents of your comment after selecting the spaces after it too into TextEdit and hitting backspace crashes on macOS Catalina. ¯\_(ツ)_/¯ It appears it split my cursor in two???? – Pixelated Fish Jan 31 at 21:14

161 Answers 161

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⁧19 فبراير - تم جمع 0 من أصل 211


Something for me to edit. I need more characters. Hi. This is text that I'm adding. Hiiiii. Hi again Test. Another thing.


To create a link, use text here

This is that


[A draft for the expansion of a deleted answer in Build a Turing *incomplete* language]

This is the full list of predefined macros (it's possible to see that only __DATE__, __TIME__ and __TIMESTAMP__ are not deterministic. Remark: defining SOURCE_DATE_EPOCH will not affect the __TIMESTAMP__)

The directives that can read the hard drive is #include, #include_next and #import.

This is the full list of directives.

While it's sufficient to provide an implementation of some basic arithmetic operations, I'd like to explain the method in more details.

Input-dependent computation

In order to make the program powerful enough, it must be possible to make the amount of computation dependent on the size of the input.

This can be achieved by encoding a natural number $n$ as a sequence of $n$ pair of brackets ()()()...()()().

So if there are two macros defined like this (there must be two to avoid it being blue-painted)

#define a() X b()
#define b() X a()

Then a()()...()() will expand to X X ... X X a.

It's usually convenient to remove the last a. That can be done by pasting the whole thing with something like _delete_this and #define a_delete_this.

Repeated fixed function call

Let x be a parameter, with its value being a sequence of $n$ ()s.

Then it's possible to generate f( repeated $n$ times and ) repeated $n$ times.

With some simple manipulation, it's not hard to define some macro $P(n, args...) to expand to f(f(...(f(args))...)) for a fixed function f.

Repeated dynamic function call

Unfortunately, this technique alone won't be able to implement $P(n, f, args...) = f(f(...(f(args))...)).

(this is not necessary for the computations, but it's more convenient this way)

Define an auxiliary macro $M: $M(f, args...) expands to f, f(args).

(note that args... is a GNU CPP extension; however this is only for convenience, all usages of it can be replaced with the standard __VA_ARGS__ identifier)

Observe that $M($M($M(f, args...))) will expands to:

$M($M(f, f(args)))
$M(f, f(f(args)))
f, f(f(f(args)))

Taking the second argument will result in f(f(f(args))).

In reality, some defer/eval is required to make the expression expands correctly.

Then, use the previous macro $P to evaluate $M $n$ times on f, args..., and it's possible to get f applied on args... $n$ times.

At the moment, it's possible to use $P to implement the multiplication function:

#define mul_1(x,y) x y, y
#define mul(x,y) $P(x,mul_1, ,y)

In this example, mul_1 is repeatedly applied on the argument (<empty>, y) $x$ times. For each application, mul_1 transforms (accumulator, y) to (accumulator+y, y); therefore after $x$ iterations the result is (x*y, y).


Let's say, you want to implement a function that uses $P based on another function that uses $P.

#define add(x,y) x y
#define pre_1(x,y) y,y()
#define pre(x) $P(x,pre_1,,) // <-- this function uses `$P`
#define sub(x,y) $P(y,pre,x) // <-- this function uses `pre`
// similar to the implementation of subtraction using pair in lambda calculus
// returns x-y if x>=y, 0 otherwise.
// (terribly inefficient.)

This will immediately raises a problem -- the inner $P is not expanded.

Which makes sense, because the inner $P is created during the expansion of the outer $P.

There's a trivial workaround for that problem, however -- define a function $P2 with the same definition as $P (and its helper functions)

This restriction makes sense, because cpp is not Turing-complete and it should not be possible for two functions to call each other.

Some example functions

With these tools, it should not be too hard to build some simple functions. Ideas from lambda calculus should be useful here.

#define equ(x,y) sub((),sub(x,y) sub(y,x))
// return 1 == () if x and y are equal, 0 == <empty> otherwise.

#define modz_1(result, x, y, value) result equ(x, i), x, y, y value
// modz_1(result, x, y, value) = (result + [x == value], x, y, value + y)
// x and y are the dividend and the divisor.
// value iterates through the first x positive multiples of y,
// and check if any of them are equal to x.

#define modz(x,y) $P3(x,modz_1,,x,y,y)
// returns 1 if x is a multiple of y, 0 otherwise.
// apply modz_1 on (0, x, y, y) x times, then return the first value of the result.


The Question.

In July 2015, the insert image feature of the toolbar of the Stack Exchange markdown editor was changed (shortcut Ctrl+G, displayed as the icon "toolbar button to insert image" ).

The behavior since then has been to make the image clickable by default - by adding an extra link to the image itself.1, 2

But the official help pages - Meta Stack Exchange markdown formatting help on how "images can be added primarily by using the the editor toolbar button "toolbar button to insert image"
" (see Images at the bottom of the page) and Meta Stack Overflow markdown editing help on images - have still not been updated to reflect this change (now more than five years later).

Shortly after I posted this question/request, a moderator and Senior Product Support Specialist wrote in a comment that the syntax for images was not changed and is still the same, concluding the syntax in the help pages is correct. - Which indeed is true if you take on a very narrow fail-of-conformity attitude concerning what help and guidance is needed to settle whether a suggested edit should be accepted or rejected.

Let me use a pilot case to explain why I think that a well-thought-out update of the help pages would benefit us all. To see the revision history of the question I have in mind, click on the image below, possibly holding down Ctrl+Shift (if you want it to open in a new tab).

Revision history of question Converting a POSTMAN request to Curl.

If you study the revisions of that question, you will notice that edit number 2 was rolled back. The editor who rolled it back commented: @Henke That edit has made the post worse.

Just to be clear - I completely agree that rolling back the edit was the right thing to do. But the question remains: on what grounds? Just referring to gut feeling? Or by saying the edit made the post worse? Without any further references this is simply not good enough or acceptable as a motivation. Out of respect for both the editor and the reviewers we must be capable of doing better than that!

Let me for a moment put myself in the shoes of the editor/reviewers of the edit that made the image non-clickable. Suppose I go to one of the help pages, such as the Meta Stack Exchange help about adding images. The current content about images is shown below.3

Meta Stack Exchange help on how to add an image

If the editor in this case did their homework and read the help page, they would conclude that an image can be input similarly to adding a link by using the suggested syntax:4
![sample image](https://example.com/img.jpg)
Judging from this help page neither the editor nor the reviewers did anything wrong!

Why on earth would they look any further? In my mind this is exactly how a help page is supposed to work. You look up whatever information you need and apply whatever syntax you find there. Bear in mind that a first-time reader might not even consider that an image could be clickable.

I have taken the liberty of supplying an answer of my own, so that you can vote it up or down however you like.5

When can we expect the help pages to be updated?

From now on, the image uploader automatically wraps images in a link to themselves
Meta Stack Exchange help on how to add an image via "toolbar button to insert image"
Meta Stack Overflow Markdown Editing Help: Images
The recommended syntax for an image with a link
Extra square brackets and numbers when using automated link or add picture feature in ...
Why does the images index on Stack Overflow appear twice?

1 The previous default behavior was to just display the image - without any click link.
2 If you are curious to learn more about how this works, see the reference list. - Or simply click the Edit feature of this question and start reading the markdown code. I have included a few different styles and methods on how to make an image clickable or non-clickable.
3 If you find it difficult to read the text in the image, click on it, and then on the back arrow of your web browser.
4 Of course, this syntax will not result in a clickable image.
5 There is nothing personal about these downvotes. It is just an elegant way of finding out the opinion of the community as a whole.


when i run this program it giving me only none

Var code = too much

this is a lot of code

help I'm stuck in a codeblock



Lots of code

Lots and lots
Var code = too much

this is a lot of code

help I'm stuck in a codeblock



Lots of code

Var code = too much

this is a lot of code

help I'm stuck in a codeblock




Lots of code
  • @ankii seeing if I get the warning that it’s mostly code (see here). – anon Sep 15 '19 at 16:31
  • [mre] does this work (typed [mre]) – anon Sep 22 '19 at 5:13
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    @ankii oh that pinged you :P? – anon Sep 22 '19 at 5:15

This is an attempt at a Community-wiki answer that responds affirmatively to the proposal:

Tags should be reviewed before they are created.

The aim is to ensure that only quality tags are created .

This answer is a mishmash of opinions that have come up in non-Community-wiki answers, along with some new views not previously brought up. It's a bit of a summary as well.

  • The reputation gate needed for suggesting new tags should remain unchanged at what is currently 5 reputation points. 1

  • A proposal for a new tag should always include a usage guidance and a tag wiki description for the tag. Both? Or at least one? 2

  • A proposal for a new tag should enter the already existing review queue for tag wiki edits. Thus, the reputation gate for voting to accept or reject a proposal for a new tag will be 5,000. 3

  • Give an option to tag proposers to link their newly created tag with another existing tag that is closely related. 4

  • No need for any approval time expiration. 5

  • StackOverflow tags are a folksonomy.9

1 Not previously proposed here. Reference:
Privileges > participate in meta.

2 Reference:
make at least one of them required.

3 References:
Use the Suggested Edits Review Queue
Privileges > approve tag wiki edits.

4 Reference:
This way, users can filter on the existing tags.

5 Reference:
I think having a approval time is not a good idea as I imagine this queue will grow substantially.

9 References:
I think it should be more towards the folksonomy end.
Tag Folksonomy and Tag Synonyms.


Testing for the truck hat.

More words since body requires 30 characters.


Not a big deal maybe, but can we make a synonym of ?

There are 16 questions tagged of which all were asked in 2016.
The tag was created in August 2016.

There are (currently) 1,026 questions tagged of which the oldest was asked in 2014 and the latest in 2021 (yesterday actually). The tag was created in April 2014.

The usage guidance (excerpt) of says:
Use [...] when multiple tags should [...] redirect to the same tag [...].

The usage guidance (excerpt) of says:
A request to add one tag as the synonym of another tag.

My suggestion:


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