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Comment by nikhilsimha | Hacker News Reader

This blew my mind. Mostly because I haven't come across this during 8 years of c++ use for professional/competitive programming.

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I've never seen anyone use these since they appeared in the spec decades ago. They're as pointless as trigraphs, which I've never seen in the wild either.

Ever seen a real use of `operator"" _X`, the C++11 feature that lets you declare a literal constant like this?

  int operator"" _km(unsigned long long);
  auto distance = 42_km;

The breadth of crazy features in C++ is really huge, when you dig in.

The equivalent thing in D is, but without a special feature:

    template _km(ulong v) { enum _km = inKilometers(v); }
    auto distance = _km!42;

It's used by the Sargon library to create a halffloat type:

https://digitalmars.com/sargon/halffloat.html

I haven't seen it used in C++, though my C++ experience post this feature is limited.

All the time,

    "A safer string"s

Declares a std::string constant.

While I agree C++ is huge, I doubt anyone would survive a Python, Java, C#, VB.NET, JavaScript, Typescript, Fortran, Ada, Common Lisp, COBOL, C pub quiz, based on the very latest language versions.

https://github.com/nlohmann/json/blob/c215b77936591d4fe0aa0a...

Congratulations! There's one!

One thing is, for the longest time MSVC did not support them (against the spec like always) so they could not be used if you wanted cross-platform code.

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