How can I hook a windows api, any sample?
What do you mean by hooking a windows api? Can you tell what you have tried? Can you show code in language X which demonstrates what you want (of course mention the libraries you use there)?
in CSharp maybe：
public static extern int SetWindowsHookEx(
You code does not show what you actually want to achieve, but only how you import a function from a DLL (you are usign FFI). Since I never did FFI (on windows with rust) nor used WinAPI (in general), I used the terms “WinAPI” and “user32” to look something up on crates.io and discovered 2 crates, maybe they can help you:
The latter may be very low level though.