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Come on, guys, I’m trying to understand the pointer-pointer behavior, but I can’t figure it out. Well, I already have an idea that the pointer points the memory address of something, to another location, thus facilitating the use, but when I create a pointer pointer, everything is already confused.
Follow the example, the idea is to create items to dynamically allocate in the Map, but I can’t understand how the "**list" will group several allocations of different items? And how I can query the address of each item?
typedef struct _item
{
int conta; //contador
char *termo; //palavra
} Item;
typedef struct _mapa
{
int total; // número de itens no mapa
int blocos; // número de blocos de itens alocados
Item **lista; // vetor de ponteiros para itens
} Mapa;void
I even tried to create a way to allocate a new item, but because I didn’t understand the **list behavior, I couldn’t locate the location to add the new allocation. **list becomes a kind of Matrix?
insere_termo (Mapa *mp, char *s)
{
Item * it = malloc (sizeof(Item));
it->termo = s;
it->conta = 1;
mp->lista = ⁢
}
If you will place more than one item
mp->lista, you first need to allocate memory tomp->lista, saying how many elements you intend to allocate, something likemp->lista = calloc(x, sizeof(*mp->lista)), where x is the amount of elements allocated, then you can insert into the list using array notation, something like:mp->lista[i] = item, whereiis the Indian. And detail, unless you have consulted the C specifications in the ISO and are very sure of what you are doing, never get the name of a namesake with_, as in_itemand_mapa.– Vander Santos
I knew, I would then have to allocate X times the list to use it as a vector, so because it’s a static allocation, I can go through it like an indexed vector, all without changing the two structures I gave as an example right?
– Pedro A. Pinheiro
Actually, the way I said the allocation would be dynamic, not static. If you want static allocation, you would have to change the Map struct and declare the item as
Item *lista[x].– Vander Santos