Question: I want to write a PHP code snippet in the question or answer. I searched that but Stack Overflow can insert only HTML, CSS, JavaScript snippet code.

How can I insert a PHP code snippet like below?

JavaScript snippet example:

```js
console.log('hello world');
```

Answer: 
No, probably not, you should use code blocks instead as specified in the other answers.

Adding to the other answers, here are a few extra points:

* The PHP stack snippets would use up all the server CPU/RAM which would make the whole experience slightly slower for everyone
* The PHP `mail()` function could be used to send spam email to lots of people, and, again, could overwhelm the server
* You can do all sorts of destructive things with PHP, including changing databases, and even deleting files.
* Too many requests for PHP could even put Stack Overflow offline. Yikes.
There isn't any way to run PHP code. You have to insert an additional link in your question/answer to share your PHP code snippet with fellow members.

A PHP code snippet can be shared by using the following websites:

<http://www.writephponline.com/>

<http://phptester.net/> - [My choice]

<https://www.mycompiler.io/online-php-compiler>

<https://paiza.io/en/languages/online-php-editor>

And many more. You can also google for this using "PHP code snippets online" keywords ;)