Few lesser known tricks, quirks and features of C

• libwheel

  1 7 7.5 C

  Generic data structures for the C programming language with (near) zero overhead.

> C11 added _Generic to language, but turns out metaprogramming by inhumanely abusing the preporcessor is possible even in pure C99: meet Metalang99 library.

I'm actually working on a library doing just that! It's still in very (very) early development, but maybe someone may find it to be interesting. [GitHub](https://github.com/jenspots/libwheel).

[Here](https://github.com/jenspots/libwheel/blob/main/include/wheel... the implementation of a vector. [Here](https://github.com/jenspots/libwheel/blob/main/tests/impl/st...) is a test file implementing a vector of strings.

• printbf

  6 586 0.0 Brainfuck

  Brainfuck interpreter inside printf

  

Somewhat related to this, printf alone in a loop is Turing-complete, by using %-directives like that. It was introduced in “Control-Flow Bending: On the Effectiveness of Control-Flow Integrity” (Carlini, et al. 2015) and the authors have implemented Brainfuck and an obfuscated tic-tac-toe with it.

[0]: https://nebelwelt.net/publications/files/15SEC.pdf

[1]: https://github.com/HexHive/printbf

[2]: https://github.com/carlini/printf-tac-toe

• InfluxDB

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  Power Real-Time Data Analytics at Scale. Get real-time insights from all types of time series data with InfluxDB. Ingest, query, and analyze billions of data points in real-time with unbounded cardinality.

  

• printf-tac-toe

  18 2,029 0.0 C

  tic-tac-toe in a single call to printf

Somewhat related to this, printf alone in a loop is Turing-complete, by using %-directives like that. It was introduced in “Control-Flow Bending: On the Effectiveness of Control-Flow Integrity” (Carlini, et al. 2015) and the authors have implemented Brainfuck and an obfuscated tic-tac-toe with it.

[0]: https://nebelwelt.net/publications/files/15SEC.pdf

[1]: https://github.com/HexHive/printbf

[2]: https://github.com/carlini/printf-tac-toe

• color-flood-for-amstrad-cpc

  1 3 10.0 C

  A puzzle game for 2 to 4 player. Written in portable C as an experiment: can a program with non-trivial algorithmic logic be compiled and run on an 8-bit platform? Answer: yes.

const int myarray[mysize];

* Good news: C can do compile time constant structs and array with deep self-references.

Yes, in C you can define and fully declare complex data structures that are accepted as compile-time constants, including pointers to parts of itself.

See "self-contained, statically allocated, totally const data structure with backward and forward references (pointers)?" for a previous example at https://stackoverflow.com/questions/47037701/can-c-syntax-de...

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I used this for a game on a retro machine where such a data structure avoids code which would have been several times (perhaps 10 times) bigger: https://github.com/cpcitor/color-flood-for-amstrad-cpc/blob/...

Here's another take showing two variant: where overall construct is an array then a struct: https://gist.github.com/fidergo-stephane-gourichon/792c194e1...

Suggest a related project