How to understand this define

Question

Nowadays , i was reading the APUE.and i found the function defined as below:

void (*signal(int signo, void (*func)(int)))(int);

i was confused,

Answer 1

In case you don't have access to cdecl right now, here is the cdecl output:

$ cdecl
cdecl> explain void (*signal(int , void (*)(int)))(int);
declare signal as function (int, pointer to function (int) returning void) returning pointer to function (int) returning void