OpenCSTL is a single-header C99 library mimicking C++ STL containers like vector and map using macros—no C++ needed.

How do you implement STL containers in C?

Use variadic macros for dispatch, pointer tricks for brackets, tags for type-routing. Check GitHub for guts.

Pure C Conquers C++ STL Containers: Macro Magic and Hard Lessons

C coders always hacked their own dynamic arrays and maps. Now a single-header lib delivers full STL-like API—no C++ needed. Game on for systems programming.

theAIcatchup Apr 09, 2026 3 min read

Code example of VECTOR in pure C with push_back, qsort, and bracket access

⚡ Key Takeaways

OpenCSTL replicates C++ STL API in pure C99 via macros, enabling push_back and v[i] without C++ compiler. 𝕏
Metadata-before-data trick allows direct qsort and bracket access—perf win for arrays. 𝕏
Tradeoffs include macro compile-time tax and no true generics, but ideal for embedded where C++ is banned. 𝕏

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#C macros #C programming #C++ STL in C #C99 macros #OpenCSTL #STL containers #container library

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Originally reported by Reddit r/programming

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