Calling C Functions and Linking

@cImport gives you the declarations, but the actual machine code still lives in a C library you must link against.

Most C calls need the C standard library. Tell the build to link libc so functions like printf resolve at link time.

For a quick run, pass the flag yourself. -lc links libc when you compile a single file directly.

Once linked, a C function is called just like a Zig one. You write c.printf(...) and Zig handles the calling convention.

You must pass arguments that fit the C signature. Wrong types are a compile error, since Zig knows the translated prototype.

For other libraries, name them. linkSystemLibrary tells the linker to pull in something like the math library.

A C function's return value arrives as a normal Zig value of the translated type, ready to store or test.

C has no error unions, so failures show up as return codes or a set errno. You check them the C way, by hand.

Zig does no silent conversion of your data. What you pass is what C receives, keeping the call cheap and predictable.

In build.zig you attach linking to the artifact. The same exe step that compiles your code also records its libraries.

Calling C is always import plus link: bring in the declarations, then make sure the real symbols are available to the linker.

Think about what makes a C function actually resolve.

You learned that calling C needs both the import and linking, after which C functions are invoked just like native Zig ones. 🎯