throwing an struct(with an array) through a function

knakworstje · #1 12-Feb-2004, 04:23

Problem:

I need to pass an struct to a Function. within the struct is an array, the array is two dimensional.
And the structure should handle different kinds of array sizes (char items[][] = not always of the same size)

Here is some code I have come up with till now.... if there is someone who could please shed some light on it for me.....

first I create an struct

typedef struct {
int aantal;
char titel[15];
char **items; // is this correct !?!?
} TMenu;

Then I do this:

TMenu hoofdmenu, dagmenu;

Next I Fill hoofdmenu who is an struct of TMenu:

hoofdmenu.items [][]= {
{"1 Nieuwe dag "},
{"2 Communicatie"},
{"3 Versie info "},
{"4 beheer "}
};

Lateron I pass that one to an Function:

TMenu toonmenu(TMenu menu ) //
{

}

Any help would be welcome......
greets roel

dsmith · #2 12-Feb-2004, 08:29

HI Roel. Welcome to the forums.

I don't see a problem with anything that you have done except for this here: (at least this is where my compiler grumbles):

CPP / C++ / C Code:

hoofdmenu.items [][]= {
		{"1 Nieuwe dag  "},
		{"2 Communicatie"},
		{"3 Versie info "},
		{"4 beheer      "}
  };

I don't think this is valid because you have already defined what hoofdmenu.items is. I think that you are going to have to assign the values in a function in line and allocate your memory at the same time. I haven't checked this syntax, but you may need to do something like(c-syntax):

CPP / C++ / C Code:

hoofdmenu.items = (char**) malloc(4*sizeof(char*));
hoofdmenu.items[0] = (char*) malloc(strlen("1 Nieuwe dag")+1);
strcpy(hoofdmenu.items[0], "1 Nieuwe dag ");

It's ugly, but I am not sure of any other way to do this. Anyone else got any thoughts?

Also, one thing about the forums here. You can highlight your code in C syntax with the c and /c switch inside of [].

knakworstje · #3 12-Feb-2004, 09:06

hi thanks for your reply.
I will look into it today or tomorrow...
greets roel

dsmith · #4 13-Feb-2004, 08:19

Hopefully you don't mind my posting unsolicited advice in this thread. I was thinking about your problem and how in all of the projects and programs I have done I rarely see a double pointer. It is not that I use arrays either. Generally, it is because I use a list in most cases. Your sample is a perfect application (IMO) for a list. You can implement this list anyway you want, but I have posted a header file that includes a full definition for a linked list here. Take a look at the posted code for how to handle this easier with a linked list:

CPP / C++ / C Code:

#include <string.h>

#include "list1.h"

typedef struct {
	int aantal;
	char titel[15];
	list*	items;
} TMenu;

TMenu hoofdmenu, dagmenu;

TMenu toonmenu(TMenu menu ) //
{
	printf("%s\n",hoofdmenu.titel);
	printf("----------------\n");
    menu.items->home();
	do{
		printf("%s\n",(char*)hoofdmenu.items->get_data());
	}while(menu.items->next());

}


int main(){

	hoofdmenu.items = new list;

	hoofdmenu.items->add_data((void*)"1 Nieuse dag");
	hoofdmenu.items->add_data((void*)"2 Communicatie");
	hoofdmenu.items->add_data((void*)"3 Versie info");
	hoofdmenu.items->add_data((void*)"4 beheer");

	strcpy(hoofdmenu.titel,"Main");

	toonmenu(hoofdmenu);
	return 0;
}

You do have to do a bit of typecasting and it does use some C++ style syntax (ie - a class), but IMO it is much more dynamic and easier to use.

knakworstje · #5 15-Feb-2004, 16:33

thanks for the help so far.

but I have decided to use an other way...
Instead of doing it al with an dynamic array I just give the number of array elements it has with an extra parameter....

It's not the stylish way I know but in the whole project it's needed about 8 times so far.....

I also think that list thingy isn't a good option for me, cause I am restricted to C and only C. because of the compiler, its not for ordinary computer but different kind of hardware.

Thanks for your help
roel

dsmith · #6 15-Feb-2004, 17:20

Yep. This is sometimes the best way to go. I was considering rewriting my list implementation to use c-syntax only anyway. If you want to consider using a list, I could do this pretty quickly.

Anyway you go, good luck!

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search
Rate This Thread
Rate This Thread:

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
c: array comparison	jack	C Programming Language	7	26-Jan-2004 12:21
Sorting a 2D array c++	mike3340	C++ Forum	4	15-Dec-2003 14:35
Extra null element in an array	samtediou	MySQL / PHP Forum	2	11-Dec-2003 12:52
i/o: set value x (long) before it is used by a function	gmn	C Programming Language	1	18-Nov-2003 02:12
deleting from an array	ionyka	C++ Forum	1	02-Sep-2003 04:09