Factor can directly call C functions in native libraries. It is also possible to compile callbacks which run Factor code, and pass them to native libraries as function pointers.
The C library interface is entirely self-contained; there is no C code which one must write in order to wrap a library.
C library interface words are found in the alien vocabulary and its subvocabularies.
Warning C does not perform runtime type checking, automatic memory management or array bounds checks. Incorrect usage of C library functions can lead to crashes, data corruption, and security exploits.