Thread: freeing dynamic 2D array

Hi!

I'm having problems freeing the Button[i].Items variable. Please take a look at the code.

Code:

typedef struct BUTTON
{
	short NoOfItems;
	char **Items;
} BUTTON_COMPONENT;

.
.
.


for (i = 0; i < 3; i++)
{
if ((Button[i].Items = (char **) malloc (sizeof (char) * Button[i].NoOfItems)) == NULL)
{
	ErrorMsg ("Button[i].Items is null!");
}
else
{
	if ((Button[i].Items[0] = (char *) malloc (sizeof (char) * (strlen ("First Button") + 1))) == NULL)
	{
		ErrorMsg ("Button[i].Items[0] is null!");
	}
	if ((Button[i].Items[1] = (char *) malloc (sizeof (char) * (strlen ("Second Button") + 1))) == NULL)
	{
         	ErrorMsg ("Button[i].Items[1] is null!");
	}
	if ((Button[i].Items[2] = (char *) malloc (sizeof (char) * (strlen ("Third Button") + 1))) == NULL)
	{
		ErrorMsg ("Button[i].Items[2] is null!");
	}
}

// do stuff

for (j = 0; j < Button[i].NoOfItems; j++)
{
    free (Button[i].Items[j]);
    Button[i].Items[j] = NULL;
}
free (Button[i].Items); // here is where the program hangs. Can someone please tell me WHY?
Button[i].Items = NULL;
}

How about this:

Code:

free (Button->Items); // not sure if this works
free (Button); // this should work just fine, but frees the entire struct rather than just 'Items'

>free (Button);

This is working just fine but this will not free entire structure. If you have pointers inside your structure you must free them first and than you can free the structure.


But, I think I found a problem.

Code:

if ((Button[i].Items = (char **) malloc (sizeof (char) * Button[i].NoOfItems)) == NULL)
{
	ErrorMsg ("Button[i].Items is null!");
}

The problem is in that sizeof (char). Now I  determine the size of char * (sizeof (char *)).

What do you folks think about that. Is this right?

Uuu, didn't see that post from Salem.

Thanks Salem.