C interop

FutureBlitz calls C directly. An Extern block declares a library’s functions in C’s types, and the program calls them with no glue code and no wrapper to compile. These tutorials cover the types and strings C uses, pointers and the Unsafe code they need, structs, callbacks, how a package names its C libraries, and fb bindgen, which writes the declarations from a header. Most programs never need any of this: std already wraps the C libraries it uses.

Tutorials

1. Calling C Declare C functions in an Extern block and call them like your own, with C's types and out-parameters.
2. Strings and buffers Pass text to C as CStrings, keep a C string alive with CString.From, and share memory with C through a Buffer.
3. Pointers and Unsafe Allocate C memory, read and write through Ptrs, and keep that code inside Unsafe blocks.
4. Structs with @CLayout Lay a Struct out as C does, pass it to C by value and by pointer, and measure it.
5. Callbacks Hand C a function or a lambda to call back, as qsort's comparison, and call a C function pointer yourself.
6. Native libraries in project.toml Name a package's C libraries in [native], static, system, or dynamic, and point Extern blocks at them with Lib.
7. bindgen Turn a C header into a FutureBlitz module with fb bindgen, and use the library through it.

The rules behind this area are in the language reference.