(*(void(*)())0)();

[Ganga]

Can any one explain the function prototype -

( * (void ( * ) ( ) ) 0 ) ( );

 

[mayflower]

Ganga 写é“：

Can any one explain the function prototype -

( * (void ( * ) ( ) ) 0 ) ( );

typedef void (*function_ptr) ();
// function_ptr is a pointer to functions without parameter and return
value

function_ptr pZero = (function_ptr) 0;
// convert 0 to function_ptr

(*pZero)();
// call the function which is pointed by pZero
// that is, call the function whose address is 0.

 

[anujanujdhamija]

I understand that statement function_ptr pZero = (function_ptr) 0;
initializes the pointer to 0 just the way non-function pointers are
initialized to NULL.

But wont a call using zero initialized function pointer as in
(*pZero)() cause program to crash?

 

[mayflower]

(e-mail address removed) 写é“：

I understand that statement function_ptr pZero = (function_ptr) 0;
initializes the pointer to 0 just the way non-function pointers are
initialized to NULL.

But wont a call using zero initialized function pointer as in
(*pZero)() cause program to crash?

Yes. I cannot remember it exactly, but I think I saw it in <<C Traps
and Pitfalls>>.

The author take this example to show how the function pointer works.
And the example came from a real project, in which a routine at
*ADDRESS 0*
needs be called when the system startup. However, the example is very
special.