Quite a time ago, my colleague accidentally committed a Youtube url to our Java codebase (middle-click accidental paste, no code review at that time). We had some laughing moments when we discovered it, as it was compelling evidence that he was watching videos during work, and even we knew what he was watching at that time.

Clearly, the "http:" is parsed as a label (for goto), and the subsequent "//", as a C++ or C99 comment. This shouldn't give you more than a moment's pause if you know C.

Or if you use a syntax highlighter.

Yes, I don't know why people are downvoting me. Have these people never seen C code using goto-based error handling?

I mean, I’ve not written C code in decades¹ and this didn’t cause a second’s pause.

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1. Long enough ago that the only practical way to get syntax highlighting was to run a separate program on the source code to generate a TeX document.

I wouldn't be surprised if a fair majority of them have been taught to see goto as nothing but a vestige of the 70s which should never be used under any circumstances except as a meme or to deliberately obfuscate code.

I have recently become quite fond of goto-based error handling and find it a lot cleaner and more readable than the if-else-mountains you otherwise end up with. I just make sure to leave a comment with a link to xkcd.com/292 so anyone else reading it knows I'm aware of what I'm doing. Now with this URL trick I can do both in one line. :)

And the corresponding `goto http` is the chef's kiss :D love it

Nice.

Another neat comment-based construct is the good old:

  //*
     foo
  /*/
     bar
  //*/

It yields 'foo' as is, and 'bar' if the first slash is removed.

It's not as needed in C given that you can use #if 1

It is handy in C derivatives, though.

Of all the (ahem, not as many as hoped) things C++ got right, // comments are one of the best ones

And I'm glad it now is part of C as well

I remember working on some code back in ’99 when the other dev on the project used // comments in C code which, it turned out, were supported by the C compiler we were using, but which broke the embedded SQL preprocessor.

This puzzle would become extra trivial with syntax highlighting.

You can only have one URL for each scheme though, else your compiler will report something like

error: redefinition of label 'https'

At least when using -Wall the compiler will give you the warning

  <source>:5:5: warning: label 'https' defined but not used [-Wunused-label]

as a hint.

That's exactly how we found an accidental copy/paste of an internal URL in our source code.

I do this to embed shell commands at the beginning of short one-file C/C++ programs to execute when hitting an F key in my text editor. I usually put very basic compile-and-run commands. It's wrapped in #if and #endif which are comments in many shells. I end the commands with exit so it doesn't try to execute the code as commands.

This is why you should only use /* */ as your comment style.

How is this related to the article?

Solve the puzzle and you'll know :-)

It's a joke

My bad, I thought you are serious.

Wouldn't there be a warning about an unused goto label

This is very neat.