Simple randomstr function in a header-only C89 library. Just #define RANDOMSTR_IMPLEMENTATION once-only in your program (before including the header).

const char* generate_random_string(const size_t length);

• CMake (3.19 or later)
• C compiler (any that work with CMake, and were released within the last 30 years)

mkdir build && cd build
cmake ..
cmake --build .

The code is distributed under BSD Zero Clause License.