Question About Structure Initialization For REAL Expert

OK, let's say that have a function menu structure declaration
like this (since I basically do):

typedef struct function_item {
char *descrip;
void(*function)(void);
} t_function_item;

typedef struct function_menu {
unsigned short num_items;
unsigned short default_item;
char *title_prompt;
t_function_item *function_items;
} t_function_menu;

Now sometimes (really just about all the time) I want to initialize it to
literal values. So this is how I do it (sort of) for a local function that
selects
a function and runs it (code that doesn't illustrate the question elided):

void my_function_1(void) {
}

void my_function_2(void) {
}

unsigned short run_function_menu(t_function_menu *function_menu) {
}

void select_function(void) {
static t_function_menu my_function_menu=
{0,0,"My Function Menu"};
static t_function_item my_function_items[]={
{"My Function 1",my_function_1},
{"My Function 2",my_function_2},
{NULL,NULL}};
my_function_menu.function_items=my_function_items;

run_function_menu(&my_function_menu);
}

My question is: for some reason if I try to initialize the menu
structure in one fell swoop, with what seems to me to be a legal
initialization, like this:

static t_function_menu my_function_menu=
{0,0,"My Function Menu",(t_function_item []){
{"My Function 1",my_function_1},
{"My Function 2",my_function_2},
{NULL,NULL}}};

I just get a bunch of syntax errors, but to me, the above seems
to be functionally identical to what I actually have to do as shown in
the select_function() example to get the thing to work...why am I
getting the errors, and IS there some way to initialize such a structure
in one initialization assignment? What am I missing here?

---
William Ernest Reid

re: Question About Structure Initialization For REAL Expert

Bill Reid wrote:

<snip>
What errors?

The code looks fine. Are you using a C99 compiler?

--
Ian Collins.

re: Question About Structure Initialization For REAL Expert

On Jul 20, 3:43 am, Ian Collins <ian-n...@hotmail.comwrote:Don't feed the troll.

re: Question About Structure Initialization For REAL Expert

vippstar@gmail.com wrote:Sorry, quiet Sunday afternoon!

--
Ian Collins.

re: Question About Structure Initialization For REAL Expert

Ian Collins wrote:--
+-------------------+ .:\:\:/:/:.
| PLEASE DO NOT F :.:\:\:/:/:.:
| FEED THE TROLLS | :=.' - - '.=:
| | '=(\ 9 9 /)='
| Thank you, | ( (_) )
| Management | /`-vvv-'\
+-------------------+ / \
| | @@@ / /|,,,,,|\ \
| | @@@ /_// /^\ \\_\
@x@@x@ | | |/ WW( ( ) )WW
\||||/ | | \| __\,,\ /,,/__
\||/ | | | jgs (______Y______)
/\/\/\/\/\/\/\/\//\/\\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\
================================================== ============

fix (vb.): 1. to paper over, obscure, hide from public view; 2.
to work around, in a way that produces unintended consequences
that are worse than the original problem. Usage: "Windows ME
fixes many of the shortcomings of Windows 98 SE". - Hutchinson

re: Question About Structure Initialization For REAL Expert

Ian Collins wrote:Where are you? It's 9 PM Saturday on the US East Coast. It's 15 hours
later in Sydney of course which would make it Sunday noon.

--
Joe Wright
"Everything should be made as simple as possible, but not simpler."
--- Albert Einstein ---

re: Question About Structure Initialization For REAL Expert

Joe Wright wrote:Sunny NZ.

--
Ian Collins.

re: Question About Structure Initialization For REAL Expert

On Jul 20, 5:27*am, "Bill Reid" <hormelf...@happyhealthy.netwrote:
Compound literals allowed only in C99. A C99 compiler should not
complain.

re: Question About Structure Initialization For REAL Expert

On Sun, 20 Jul 2008 12:43:23 +1200, Ian Collins wrote:[[ context:

static t_function_menu my_function_menu=
{0,0,"My Function Menu",(t_function_item []){
{"My Function 1",my_function_1},
{"My Function 2",my_function_2},
{NULL,NULL}}};

in a function ]]
A C99 compiler is supposed to complain for the code Bill posted. It's not
supposed to treat this as a syntax error, but it is supposed to complain
about this, and it is extremely likely to make this an error anyway. You
can't initialise a static object using a pointer to an auto object.

re: Question About Structure Initialization For REAL Expert

Harald van Dijk wrote:Which auto object?

--
Ian Collins.

re: Question About Structure Initialization For REAL Expert

On Sun, 20 Jul 2008 20:38:49 +1200, Ian Collins wrote:(t_function_item []){
{"My Function 1",my_function_1},
{"My Function 2",my_function_2},
{NULL,NULL}}

A compound literal in a function definition has automatic storage
duration. There is no exception for initialisation.

re: Question About Structure Initialization For REAL Expert

rahul <rahulsinner@gmail.comwrites:
Yes it should (at last I think it should) -- the object is static.
You can just make the whole menu automatic (see my reply).

--
Ben.

re: Question About Structure Initialization For REAL Expert

Ben Bacarisse <ben.usenet@bsb.me.ukwrites:
<snip>I missed the () introducing a compound literal. Curiously the rest of
my answer is correct and helpful!

The errors will either be (a) not using a C99 compiler or (b) the
correct complaint that a static is being initialised with a compound
literal.

--
Ben.

re: Question About Structure Initialization For REAL Expert

"Bill Reid" <hormelfree@happyhealthy.netwrites:
<snip><snip>Hmm... are you using lcc-win32? This program:

#include <stdio.h>
#include <stdlib.h>

typedef struct function_item {
const char *descrip;
void(*function)(void);
} t_function_item;

typedef struct function_menu {
unsigned short num_items;
unsigned short default_item;
const char *title_prompt;
t_function_item *function_items;
} t_function_menu;

void my_function_1(void)
{
printf("in %s()\n", __func__);
}

void my_function_2(void)
{
printf("in %s()\n", __func__);
}

void run_function_menu(t_function_menu *function_menu, int item)
{
if (item < 0 || item >= function_menu->num_items)
item = function_menu->default_item;
printf("Do #%d %s: ", item, function_menu->function_items[item].descrip);
function_menu->function_items[item].function();
}

int main(int argc, char **argv)
{
t_function_menu my_function_menu = {
2, 0, "My Function Menu",
(t_function_item[]){
{"My Function 1", my_function_1},
{"My Function 2", my_function_2},
{NULL, NULL}
}
};
run_function_menu(&my_function_menu, argc 1 ? atoi(argv[1]) : 0);
return 0;
}

runs fine using gcc but gives a segmentation fault using lcc-win32.
It looks like a general bug in the way structs get initialised to me.
Take this, for example:

#include <stdio.h>

int main(void)
{
int array[] = { 1, 2, 3 };
struct s {
int n;
int *items;
} s = { 3, array };
printf("%p %p\n", (void *)array, (void *)s.items);
return 0;
}

s.items does not get initialised.

--
Ben.

re: Question About Structure Initialization For REAL Expert

"Bill Reid" <hormelfree@happyhealthy.netwrites:
<snip><snip>It was just a guess.

<snip>Yes, in C90 all initialisers must be "compile-time constants" so a
pointer to an automatic variable is not allowed.
Yes, that is all standard and correct. If you are tied to C90 (=C89)
then it also explains your initial syntax errors. You originally
posted code that contained a compound literal (a C99 feature) and your
compiler would very likely reject it. That's why I went off on the
C99 tangent -- I thought is was available to you.

--
Ben.