Can you help me explaining the following C code?

Question

int main(int argc, char **argv)
{    
   int (*func)();    
   func = (int (*)()) code;   
   (int)(*func)();    
}

the variable code has some shellcode in it

Answer 1

Function pointers. This code snippet should help you understand.

#include <stdio.h>
int Hello();
int code();

int main(int argc, char **argv)
{    
   int (*func)(); //pointer to function that takes no arguments quivalent to: int (*func)(void);
   func =&Hello;
   int x = func();
   printf("%d\n", x);

    func = (int (*)()) code; // Assigns the pointer from the code function to the func pointer
    x = code();
    printf("%d", x);
}
int code()
{
    printf("code returns: ");
    return 500;
}

int Hello()
{
    printf("hello returns: ");
    return 1;
}

Answer 2

code probably is a variable that correspond to the address of some machine code in memory. Then a pointer to function that takes no parameter and returns an int is set to that address and the function is called. int f() is the prototype for a function with no param and int as return value, then int (*pf)() is a pointer to such a function.