Re: typedef with function pointers

vardhan <vardhanw@xxxxxxxxx> writes:

On Sep 30, 1:52 pm, Tor Rustad <tor_rus...@xxxxxxxxxxx> wrote:
Googy wrote:
Hi!!
Can any one explain me the meaning of following notations clearly :

1. typedef char(*(*frpapfrc())[])();
frpapfrc f;

2. typedef int (*(arr2d_ptr)())[3][4];
arr2d_ptr p;

3. typedef int (*(*(*ptr2d_fptr)())[10])();
ptr2d_fptr q;

4. typedef char (*(*arr_fptr[3])())[10];
arr_fptr x;

5. typedef float *(*(*(*ptr_fptr)())[10])();
ptr_fptr y;

What are f,p,q,x,y?? and how?
Please don't just answer what they are explain then clearly..

homework-o-meter = 100%

Hint: cdecl

Heres are quick question:

A typical typedef for a data type like a struct goes like:

typedef struct X { ...} XStruct;

where XStruct is now "struct X". Why don't we follow a similar way to
define function pointers?

We can, but the pointers are the problem. For example:

typedef int XFunc(void);

defines XFunc to be a name for the type "function of no parameters
returning int". There is an exact equivalence between this and the
code you posted to typedef a "struct X".

If you want a typdef for a pointer to a "struct X" we just add a star,
because the syntax works:

typedef struct X { ... } *XStructPtr;

but you can't just add a star in front of XFunc above because in that
case the start will be associated with the return type of the
function:

typedef int *XFunc(void);

This is a synonym for "function of no parameters returning a pointer
to int". To alter this association, we need brackets:

typedef int (*XFuncPtr)(void);

Now XFuncPtr is "pointer to function of no parameters returning an
int". Of course. given the first simple typedef, we can use it to
define the second more easily:

typedef int XFunc(void);
typedef XFunc *XFuncPtr;

and many people prefer to do this for complex point to function (and
array) types.

Or is it that the placement of the type
defined follows a similar rule for both these declarations?

I could not understand that. I hope you did not mean what I just said
at great length!

--
Ben.
.

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