From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Mariano Moreyra" <moremari@aca.org.ar>
Subject: RE: named structure members
Date: Thu, 11 Sep 2003 11:41:34 -0300
Sender: linux-c-programming-owner@vger.kernel.org
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References: <20030911142642.GD14403@3d-computers.co.uk>
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To: 'Matthew Harrison' <matth@3d-computers.co.uk>
Cc: linux-c-programming@vger.kernel.org

Ok... I understood that what you wanted was to name your structure members
dynamically.
But if you will only have those for members, that's a good approach
Now, are you allocating memory for your strings before doing a strcpy??
Because you defined your members like char pointers, you have to dynamically
allocate some memory form them before use.
You could define your members like arrays instead of char pointers (i.e char
db_host[256])


------

this is getting very complex.

here is the struct that i want my config to go into:

<snip>
typedef struct _CFG_struct
{
       char *db_host;
       char *db_name;
       char *db_pass;
       char *db_user;
}CFG;
</snip>

and I am doing the following (pseudo code)

<snip>
for(i = 0; i <= array_of_config_items; i++)
{
	keyword = array_of_config_items[i];

	while (read_config_file != EOF)
	{
		check_return_value;
		if keyword = 'item1'
		{
			item1 = value;
		}
		elsif keyword = 'item2'
		{
			item2 = value;
		}
		and_so_on();
	}
}
</snip>

i can sort it now with the multiple if's but now it segfaults on
a strcpy for some reason and i'm still learning how to use gdb.

On Thu, Sep 11, 2003 at 11:03:59AM -0300, Mariano Moreyra wrote:
> > what i'm doing is stepping thru an array of different config options
> > calling the read_config_var on each one and checking the output.
> > if the output is good then i want to store the value in a member of
> > a structure. for example i want the config options to be stored like
> > this:
>
> > config.db_host = 'maiden.genestate.com'
> > config.db_user = 'root'
>
> > you get the idea. my question is how do i dynamically assign a name
> > to a structure member. I have good_values[i] which contains the
> > current config directive but if you look at line 8 of the example,
> > you can see the problem, how do i say config.good_values[i], when
> > good_values[i] is not itself a member.
>
> I think that I get the idea ...
> But are you sure that is that what you want??
> I mean, the idea is that in your config option you could have any config
> directives (or keys) and values??
> How you will handle that options later without knowing from the begining
> what options you could have??
> Anyway...I think that you could do is create your structure like this:
>
>  typedef struct {
> 	char key[255];
> 	cahr value[255];
>  } t_config;
>
>  t_config config[20];   // Change 20 and 255 to adapt to your needs
>
>
>  so your code would look like this:
>
> for(i = 0; i < n_values; ++i)
>         {
>                 strcpy(keyword, good_values[i]);
>
>                 switch (read_config_var(values_file, keyword, value))
>                 {
>                         case 0:
>                                 strcpy(config[i].key, keyword);
> 					  strcpy(config[i].value, value);
>                                 break;
>                         case -1:
>                                 printf("\nFile Error for [%s] \n",
> values_file);
>                                 break;
>                         case -2:
>                                 printf("\nBad User Parm for [%s] \n",
> keyword);
>                                 break;
>                         default:
>                                 printf("\nUnknown Error Occurred \n");
>                                 break;
>                 }
>         }
>
>
> I'm not sure if is that what you want...and if I really understood your
> problem...
> So, let me know if this mail sucks! :)
>
> --
> Mariano Moreyra <mariano_moreyra@aca.org.ar>

--
Mat Harrison
Technical Developer
3d Computer Systems Ltd.
matth@3d-computers.co.uk