Question

I’m doing something similar to the following code. I have already gone through AddtoStructFunction() filling mystruct once. Now, what I would like to do is to append every new entry directly to the mystruct without having to free mystruct and iterate over again the whole g_hash_table containing the new key(s) to insert them into mystruct.

What would be a good way of doing this? realloc each new entry?

void InsertFunction(GHashTable *hash, char *str) {
    g_hash_table_insert(hash, str, "Richmond");
}

void AddtoStructFunction(struct dastruct **mystruct) {
    // initial fill with all elements of g_hash_table_size(g_hash_table) at the time AddtoStructFunction is called.
    mystruct = (struct dastruct **)malloc(sizeof(struct dastruct *)*g_hash_table_size(g_hash_table));
    g_hash_table_iter_init(&iter, g_hash_table);
    while (g_hash_table_iter_next(&iter, &key_, (gpointer) &val)) {
        mystruct[i] = (struct dastruct *)malloc(sizeof (struct dastruct));
        mystruct[i]->myKey = (gchar *) key_;
        i++;
    }
}

void AddExtraOnes(struct dastruct **mystruct, char *string) {
    // realloc mystruct here?
    // each time I call AddExtraOnes, I'd like to append them to mystruct
    mystruct[?]->myKey = string;
}

int i;
for(i = 0; i < 100000, i++){
    InsertFunction(g_hash_table, "RandomStrings");
}
AddtoStructFunction(mystruct);
...
// do this n times
AddExtraOnes(mystruct, "Boston");

Answer 1

You can use the realloc function to reallocate your array of struct pointers. It will copy the existing data to the new array if it succeeds (if you have an array of 20 pointers to mystruct instances and realloc the array to contain 30, the first 20 will be the same as your original array).

Since you’re using GLib, you might also consider GArray rather than a plain mystruct**. It handles re-allocation for you.