Two structs for a linked list in C

Question

Ok I am creating an ADT for a singly linked list. I have a Struct name List that stores the pointer to the first node(first item in the list, which is also a struct)and size. The node stores first name and a pointer to the next node. Here are the sturcts:

typedef struct List *ListP;

struct List{
   ListP head;
   int size;
   };

struct node{
   char name[20];
   nodeP next;
   };

First I called malloc to give me memory for struct List:

ListP newList;
    newList = malloc(sizeof(struct List)); //should I typecast this to (ListP *)?
    if (newList == NULL){
         fprintf(stderr, "Memory allocation failed");
    }
    else{
        newList->head = NULL;    
        newList->size = 0;       
    }

Then I called malloc again to give me memory for the first node:

struct node *new;
    newNode = malloc(sizeof(struct node));
    if (newNode == NULL){
         fprintf(stderr, "Memory allocation failed");
    }
    else{
        newNode->name = 'Jay';
        newNode->next = NULL;

Now that I have my List and a new node, I assigned list->head to the address of the new node;

newList->head = newNode;

Untill this time the compiler doesn't complain. But when I try to access the elements in the first node using the pointer that I have for the list:

name = newList->head->name;

The compiler complains that struct List has no member named 'name'

How can I access the field in struct node, assuming that I only have pointer to the struct List and List->head is pointing to the first node. Any help would be appreciated.

`typedef struct node *nodeP;` .. `ListP head;` --> `nodeP head;` — BLUEPIXY, Oct 04 '14 at 21:47
[In C you should not cast the result of `malloc`](http://stackoverflow.com/questions/605845/do-i-cast-the-result-of-malloc). — Some programmer dude, Oct 04 '14 at 22:02

score 2 · Accepted Answer · answered Oct 04 '14 at 21:47

You declared head as a ListP when it should be of type NodeP assuming that NodeP is a node*.

Try being consistent with names. Here is a suggested revision:

// forward declarations
struct List;
struct Node;

typedef struct List *ListP;
typedef struct Node *NodeP;

struct Node{
   char name[20];
   NodeP next;
};

struct List{
   NodeP head;
   int size;
};

Two structs for a linked list in C

1 Answers1