This repository provides a single-header C/C++ library (utf8.h) for UTF-8 string manipulation. It implements a comprehensive set of functions mirroring the standard C string.h and strings.h APIs, but operating on UTF-8 encoded strings with codepoint-aware semantics. The library includes functions for length calculation (utf8len), comparison (utf8cmp, utf8casecmp), concatenation (utf8cat), searching (utf8chr, utf8str, utf8casestr), validation (utf8valid, utf8makevalid), case conversion (utf8lwr, utf8upr), and codepoint extraction (utf8codepoint, utf8rcodepoint). It supports C++14 constexpr for many functions and C++20 char8_t. The code is highly portable, tested across multiple compilers (gcc, clang, MSVC, tcc) and platforms (Linux, macOS, Windows), and includes extensive unit tests covering edge cases like invalid sequences, truncated strings, and case mapping for Latin, Greek, and Cyrillic scripts. The library is self-contained with no external dependencies beyond the standard C library.

utest.h is a single-header unit testing framework for C and C++ that provides automatic test registration via constructor attributes, sophisticated assertion macros with expression tracking, and cross-platform support. The framework supports basic tests, fixture-based tests, and indexed/parameterized tests. It outputs results in both human-readable console format and machine-readable XML format. The implementation demonstrates high craftsmanship through its platform abstraction layer, memory-safe test registration system, and clever use of compiler-specific features to eliminate boilerplate. The core functionality is entirely self-contained within utest.h with no external dependencies beyond standard libraries.