__LINE__ returns the line of code its on, and % 10 means “remainder 10.” Examples:

1 % 10 == 1
...
8 % 10 == 8
9 % 10 == 9
10 % 10 == 0 <-- loops back to 0
11 % 10 == 1
12 % 10 == 2
...
19 % 10 == 9
20 % 10 == 0
21 % 10 == 1

In code, 0 means false and 1 (and 2, 3, 4, …) means true.

So, if on line 10, you say:

int dont_delete_database = true;

then it will expand to:

int dont_delete_database = ( 10 % 10 );
// 10 % 10 == 0 which means false
// database dies...

if you add a line before it, so that the code moves to line 11, then suddenly it works:

// THIS COMMENT PREVENTS DATABASE FROM DYING
int dont_delete_database = ( 11 % 10 );
// 11 % 10 == 1, which means true

Lol, ok there might be a little more than what meets the eye, cuz when i type `&` (without amp;) it converted it to & !!

test: ＆

＆

new challenge- try to get it to render a & instead of & inside of `` (or ``` ``` for bulk testing)

tried:

• `&`
• `&`
• `&`
• `&;`
• `&<invisible character>`
• `&divide;` still becomes `÷` weirdly enough

I kinda cheated cuz its not the same character… but I got it to show by using the japanese monospaced & (＆)

There’s not enough symbols on my keyboard, so let’s invent a code so we can write other symbols

1. lets say & means start of code
2. and say ; means end of code
3. Between the start and end is the code

Now let’s make some real symbols

• ¢ can be &cent;
• © can be &copy;
• ÷ can be &divide;

I want to tell other people how to use our new code, but if I tell them to “just write &divide;” it’ll turn my message into “just write ÷” !! So how can we fix this?

What if we make & its own code?

• &amp; —> &
• &amp;divide; —> &divide; ???

Yes! That’ll work :)

This is how &amp; came to be, and it’s specifically used in HTML as a way to write those symbols above (and escape other a few other symbols for similar reasons we did with &amp;)

As for why & shows up as &amp;, there are 2 main places I can see this happening:

1. The editor you use to write it automatically converts an & —> &amp;. But the user typed in &amp; (making it &amp;amp;). I think this is most likely. I’m guessing the title of posts automatically do the conversion, but the post body and comments do not because it uses a raw markdown editor
2. In some contexts the & specifically doesn’t get converted? like how you can write `&amp;` to get & as opposed to seeing ＆

hmm what if you use the escape code to write the escape code :P

&amp;

written as &amp;amp;

… written as &amp;amp;amp;