Linked Lists.. that contain linked lists

What should I change in this code to implement a linked list... inside every node of a different linked list...

Code:

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typedef struct _node{
    struct _Nodes_list *nlsent;
    struct _node *next;
    struct _node *prev;
} NODE;

typedef struct _Nodes_list{
    struct _Nodes_list *next;
    struct _Nodes_list *prev;
} NODES_LIST;

NODE list_add(NODE *sent)
{
    NODE *new_node;
    new_node = (NODE *)malloc(sizeof(NODE));
    sent->prev->next = new_node;
    new_node->prev = sent->prev;
    new_node->next = sent;
    sent->prev = new_node;

    new_node->nlsent = (NODES_LIST *)malloc(sizeof(NODES_LIST));
    new_node->nlsent->next = new_node->nlsent;
    new_node->nlsent->prev = new_node->nlsent;
}

                                               
NODES_LIST add_nodes_list_node(NODES_LIST *sent)
{
    NODES_LIST *new_node;
    new_node = (NODES_LIST *)malloc(sizeof(NODES_LIST));
    sent->prev->next = new_node;  //<<<<Here I get a Seg Fault.
    new_node->prev = sent->prev;
    new_node->next = sent;
    sent->prev = new_node;
                                                                                       
}

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if it helps, im getting a seg fault on the add_nodes_list_node()function on the 3rd line.. because I "havent initalized the sent->prev yet.. even though I thought i did that in list_add.. didnt I ???? What do I need to do ?

I'll tell you exactly what you need to do:

Start drawing yourself pictures.

If you aren't an experienced programmer, and you're attempting to pound this code out without some kind of visual reference, you're just asking for mistakes.

Quote:

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if it helps, im getting a seg fault on the add_nodes_list_node()function on the 3rd line.. because I "havent initalized the sent->prev yet.. even though I thought i did that in list_add.. didnt I ???? What do I need to do ?

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If you post the code that calls them it would help.

Please also read the FAQ entry about Casting malloc.

I remember posting an example for you that basically would apply to this one as well.... Why not use that as a reference? It believe it compiled fine.