Wolfram LibraryLink User Guide
Wolfram LibraryLink provides a powerful way to connect external code to the Wolfram Language, enabling high-speed and memory-efficient execution. It does this by allowing dynamic libraries to be directly loaded into the Wolfram Language kernel so that functions in the libraries can be immediately called from the Wolfram Language.
You can exchange not only C-like data types such as integers, reals, packed arrays, and strings, but also arbitrary Wolfram Language expressions. In addition, there are useful functions such as sending errors and calling back to the Wolfram Language.