array of pointers on functions

[Evangelista Sami]

hello

i haven't touch any C code for long time and i dont remember how to
declare an array of pointers on functions. i have tried this :
-----------------------
35 void firing_1
36 (firing f,
37 int *old_m,
38 int *new_m);
39
40 const void (*firing_table[1])
41 (firing,
42 int *,
43 int *) =
44 {
45 firing_1
46 };
------------------------

but the compiler says :
__firings__.h:46: warning: initialization from incompatible pointer
type

my gcc version is 2.8.1.

any idea?

thanks for any response

[Richard Heathfield]

Evangelista Sami wrote:

hello

i haven't touch any C code for long time and i dont remember how to
declare an array of pointers on functions. i have tried this :
-----------------------
35 void firing_1
36 (firing f,
37 int *old_m,
38 int *new_m);
39
40 const void (*firing_table[1])
41 (firing,
42 int *,
43 int *) =
44 {
45 firing_1
46 };
------------------------

but the compiler says :
__firings__.h:46: warning: initialization from incompatible pointer
type

Typedefs usually help in this kind of situation.

typedef void FIRING_FUNCTION(firing f, int *old_m, int *new_m);

FIRING_FUNCTION firing_1;

int main(void)
{
const FIRING_FUNCTION *firing_table[1];

firing_table[0] = firing_1;

return 0;
}
--
Richard Heathfield : bi****@eton.powernet.co.uk
"Usenet is a strange place." - Dennis M Ritchie, 29 July 1999.
C FAQ: http://www.eskimo.com/~scs/C-faq/top.html
K&R answers, C books, etc: http://users.powernet.co.uk/eton

[pete]

Evangelista Sami wrote:

hello

i haven't touch any C code for long time and i dont remember how to
declare an array of pointers on functions. i have tried this :
-----------------------
35 void firing_1
36 (firing f,
37 int *old_m,
38 int *new_m);
39
40 const void (*firing_table[1])
41 (firing,
42 int *,
43 int *) =
44 {
45 firing_1
46 };
------------------------

but the compiler says :
__firings__.h:46: warning: initialization from incompatible pointer
type

my gcc version is 2.8.1.

any idea?/* BEGIN new.c */

#include <stdio.h>
#include <math.h>

#define FUNCTION_LIST { sin , cos, tan }
#define STRING_LIST {"sin", "cos", "tan"}
#define PI_OVER_4 (3.14159265 / 4)
#define FUNCTIONS (sizeof function / sizeof *function)

int main(void)
{
double (*function[])(double) = FUNCTION_LIST;
char *string[] = STRING_LIST;
size_t result;

for (result = 0; result != FUNCTIONS; ++result) {
printf("%s(%f) is %f\n",
string[result], PI_OVER_4, function[result](PI_OVER_4));
}
return 0;
}

/* END new.c */

--
pete

[Julian V. Noble]

Evangelista Sami wrote:

hello

i haven't touch any C code for long time and i dont remember how to
declare an array of pointers on functions. i have tried this :
-----------------------
35 void firing_1
36 (firing f,
37 int *old_m,
38 int *new_m);
39
40 const void (*firing_table[1])
41 (firing,
42 int *,
43 int *) =
44 {
45 firing_1
46 };
------------------------

but the compiler says :
__firings__.h:46: warning: initialization from incompatible pointer
type

my gcc version is 2.8.1.

any idea?

thanks for any response

Jirka Klaue kindly showed me this:

double (*f[])(double) = {sin, cos, log, exp}; // array of pointers
for (i=0; i<4; i++) printf("%f\n", f[i](.5)); // ex. of use

The functions can be anything, as long as they are consistent
in the type(s) of their argument(s), and in the type they return.

Probably a good idea to prototype any functions you want to point
to _before_ you point to them in the table ;-)

--
Julian V. Noble
Professor Emeritus of Physics
jv*@lessspamformother.virginia.edu
^^^^^^^^^^^^^^^^^^
http://galileo.phys.virginia.edu/~jvn/

"Science knows only one commandment: contribute to science."
-- Bertolt Brecht, "Galileo".

[Julian V. Noble]

Evangelista Sami wrote:

hello

i haven't touch any C code for long time and i dont remember how to
declare an array of pointers on functions. i have tried this :
-----------------------
35 void firing_1
36 (firing f,
37 int *old_m,
38 int *new_m);
39
40 const void (*firing_table[1])
41 (firing,
42 int *,
43 int *) =
44 {
45 firing_1
46 };
------------------------

but the compiler says :
__firings__.h:46: warning: initialization from incompatible pointer
type

my gcc version is 2.8.1.

any idea?

thanks for any response

Jirka Klaue kindly showed me this:

double (*f[])(double) = {sin, cos, log, exp}; // array of pointers
for (i=0; i<4; i++) printf("%f\n", f[i](.5)); // ex. of use

The functions can be anything, as long as they are consistent
in the type(s) of their argument(s), and in the type they return.

Probably a good idea to prototype any functions you want to point
to _before_ you point to them in the table ;-)

--
Julian V. Noble
Professor Emeritus of Physics
jv*@lessspamformother.virginia.edu
^^^^^^^^^^^^^^^^^^
http://galileo.phys.virginia.edu/~jvn/

"Science knows only one commandment: contribute to science."
-- Bertolt Brecht, "Galileo".

[Barry Schwarz]

On 4 Oct 2003 04:33:20 -0700, ev******@cnam.fr (Evangelista Sami)
wrote:

hello

i haven't touch any C code for long time and i dont remember how to
declare an array of pointers on functions. i have tried this :
-----------------------
35 void firing_1
36 (firing f,
37 int *old_m,
38 int *new_m);
39
40 const void (*firing_table[1])
41 (firing,
42 int *,
43 int *) =
44 {
45 firing_1
46 };
------------------------

but the compiler says :
__firings__.h:46: warning: initialization from incompatible pointer
type

my gcc version is 2.8.1.

any idea?

thanks for any response

Mine processed it without any diagnostics at all once I provided a
typedef for firing. Did you cut and paste the code or re-type it?
<<Remove the del for email>>

[Micah Cowan]

ev******@cnam.fr (Evangelista Sami) writes:

hello

i haven't touch any C code for long time and i dont remember how to
declare an array of pointers on functions. i have tried this :
-----------------------
35 void firing_1
36 (firing f,
37 int *old_m,
38 int *new_m);
39
40 const void (*firing_table[1])
41 (firing,
42 int *,
43 int *) =
44 {
45 firing_1
46 };
------------------------

but the compiler says :
__firings__.h:46: warning: initialization from incompatible pointer
type

my gcc version is 2.8.1.

any idea?

thanks for any response

You have an array[1] of pointers to functions... returning const
void?!?

Maybe you wanted:

void (* const firing_table[1])(firing, int *, int *) = { firing_1 };

Array[1] of const pointers to functions... returning void.

BTW, what good is a single-element array in this case?

-Micah

[Peter Nilsson]

"Richard Heathfield" <do******@address.co.uk.invalid> wrote in message
news:bl**********@sparta.btinternet.com...

Evangelista Sami wrote:

hello

i haven't touch any C code for long time and i dont remember how to
declare an array of pointers on functions. i have tried this :
-----------------------
35 void firing_1
36 (firing f,
37 int *old_m,
38 int *new_m);
39
40 const void (*firing_table[1])
41 (firing,
42 int *,
43 int *) =
44 {
45 firing_1
46 };
------------------------

but the compiler says :
__firings__.h:46: warning: initialization from incompatible pointer
type
Typedefs usually help in this kind of situation.

typedef void FIRING_FUNCTION(firing f, int *old_m, int *new_m);

FIRING_FUNCTION firing_1;

I have an aversion to declaring function prototypes like that as they look
far too much like object declarations. YMMV
int main(void)
{
const FIRING_FUNCTION *firing_table[1];
I'm not so sure that const is a good idea.

6.7.3p8: "...If the specification of a function type includes any type
qualifiers, the behavior is undefined."
firing_table[0] = firing_1;
This assignment would presumably require a diagnostic as it discards
qualifiers.

return 0;
}

--
Peter

[Richard Heathfield]

Peter Nilsson wrote:

"Richard Heathfield" <do******@address.co.uk.invalid> wrote in message
news:bl**********@sparta.btinternet.com...

Typedefs usually help in this kind of situation.

typedef void FIRING_FUNCTION(firing f, int *old_m, int *new_m);

FIRING_FUNCTION firing_1;
I have an aversion to declaring function prototypes like that as they look
far too much like object declarations. YMMV

MMDIV, yes. My counter-aversion is to concealing pointer types inside
typedefs.

int main(void)
{
const FIRING_FUNCTION *firing_table[1];

I'm not so sure that const is a good idea.

Neither am I. Not sure how it got in there. Sorry about that.
--
Richard Heathfield : bi****@eton.powernet.co.uk
"Usenet is a strange place." - Dennis M Ritchie, 29 July 1999.
C FAQ: http://www.eskimo.com/~scs/C-faq/top.html
K&R answers, C books, etc: http://users.powernet.co.uk/eton

[Peter Nilsson]

"Richard Heathfield" <do******@address.co.uk.invalid> wrote in message
news:bl**********@sparta.btinternet.com...

Peter Nilsson wrote:

"Richard Heathfield" <do******@address.co.uk.invalid> wrote in message

typedef void FIRING_FUNCTION(firing f, int *old_m, int *new_m);

FIRING_FUNCTION firing_1;

I have an aversion to declaring function prototypes like that as they look far too much like object declarations. YMMV

MMDIV, yes. ...

Why not use the far less ambiguous explicit prototype...?

void firing_1(firing, int *, int *);

What do you gain from the use of the typedef in a function declaration?

--
Peter

[Richard Heathfield]

Peter Nilsson wrote:

"Richard Heathfield" <do******@address.co.uk.invalid> wrote in message
news:bl**********@sparta.btinternet.com...

Peter Nilsson wrote:

>
> I have an aversion to declaring function prototypes
> like that as they look
> far too much like object declarations. YMMV

MMDIV, yes. ...

Why not use the far less ambiguous explicit prototype...?

void firing_1(firing, int *, int *);

What do you gain from the use of the typedef in a function declaration?

It makes defining arrays of function pointers rather simpler. In some
circumstances, it can also make the relationship between a bunch of
function prototypes more obvious. Example from some recent demo code for
Win32:

/* this is in a library header */
typedef LRESULT MW_MESSAGE_HANDLER(HWND,
UINT,
WPARAM,
LPARAM);

/* these are in an application header */
MW_MESSAGE_HANDLER VigenereCreate;
MW_MESSAGE_HANDLER VigenereResize;
MW_MESSAGE_HANDLER VigenereCommand;
MW_MESSAGE_HANDLER VigenereDestroy;

But no, I don't typedef every single function type that I use. I do it when
it seems to me to be The Right Thing.

--
Richard Heathfield : bi****@eton.powernet.co.uk
"Usenet is a strange place." - Dennis M Ritchie, 29 July 1999.
Rudimentary Win32 programming tutorial:
http://www.rjgh.co.uk/prg/c/windows/index.html