在主体中定义name_fn的函数的C原型

Question

Could you help me understand what the following piece of code means? Specifically, I do not understand what the effect of name_fn is.

    #define name_fn
    void name_fn Function(void);

Answer 1

The macro name_fn expands to nothing during pre-processing. So the next line is same as

void Function(void);

Empty #define is useful for compatibility, self documentation and/or mechanical checking.

For example, in socket programming, you may encounter :

SOCKET WSAAPI
accept (IN SOCKET s,OUT struct sockaddr FAR* addr, OUT int FAR* addrlen );

Here IN and OUT are empty macros. They

1. Can be used to mechanically [ check ] the code.
2. Serve as a strong reminder on how the author intended use the parameters associated with them.