Fill value by value a char * - c

Question

I'm trying to fill a char *info inside a struct nodo;
This is struct :
struct nodo {
char *info;
struct nodo *prec;
struct nodo *succ;
};
typedef struct nodo nodo;
And this is whole function :
nodo *q,*t = NULL,*head = NULL;
int i, nodi=0 ;
char *c = a, *k = a;
while ( *c != '\0') {
if (*c == ' ')
nodi++;
c++;
}
for (i = 0; nodi != 0; i++) {
if (i == 0){
head = CreateFirstNodo();
t = head;}
if (i == 1)
q = CreateSecondNodo(head);
else
q = CreateNNodo(head);
nodi--;
}
char *k = a;
int i = 0;
while ( *k != '\0' )
{
if (*k == ' ' )
{
head = head->succ;
i = 0;
}
head->info[i] = *k; // ERROR EXC BAD ACCESS
i++;
k++;
}
return t;
}
k is a char* and should scroll the char[] to which is assigned and should copy any of his values to the proper place in head->info[i] which is char *info in struct
if k hits a space, the nodo goes to the next nodo and the 'i' become 0 again since i need a word filled in each nodo.
BUT this code shows error EXC BAD ACCESS in the marked line.
Here are the 3 CreateNodo functions:
nodo *CreateFirstNodo() {
nodo *q;
q = malloc(sizeof(nodo));
q->prec = NULL;
q->succ = NULL;
return q;
}
nodo *CreateSecondNodo(nodo *head) {
nodo *q;
q = malloc(sizeof(nodo));
q->succ = NULL;
q->prec = head;
head->succ = q;
return q;
}
nodo *CreateNNodo(nodo *head) {
nodo *q;
while (head->succ != NULL) {
head = head ->succ;
}
q = malloc(sizeof(nodo));
q->succ = NULL;
q->prec = head;
head->succ = q;
return q;
EDIT: sorry for lacking code.

Answer 1

You're attempting to dereference an uninitialized pointer, probably (an initialization is not shown).
When you access info[i] what it does is add info + i and use that as an address to find a char. If info has an invalid value (such as NULL), then you get the error you see.
You probably need to initialize info with something like info = malloc(size_i_want), but it's hard to see what you're trying to achieve here.

Answer 2

The reason you get EXC BAD ACCESS is because you never actually allocate memory for info. In your struct nodo you have info defined to be a pointer to a character, but you never have any memory allocated for it.
Depending on how big your input could be you could either do char info[256] (or whatever size you want) or you could calloc the amount of space you want in Createxxxx functions.
Additionally, you really only need one Create function. I would do something like this:
nodo *CreateNodo(nodo *head)
{
nodo *q;
q = calloc(1, sizeof(nodo));
if (q) {
//assume info should be 256 chars
q->info = calloc(256, sizeof(char));
if (!q->info) {
free(q);
return NULL;
}
q->succ = NULL;
q->prec = NULL;
if (head) {
while (head->succ != NULL) {
head = head->succ;
}
q->prec = head;
head->succ = q;
}
return (q);
}
That way you only have 1 function to debug/fix.