Linked Lists.. that contain linked lists

This is a discussion on Linked Lists.. that contain linked lists within the C Programming forums, part of the General Programming Boards category; What should I change in this code to implement a linked list... inside every node of a different linked list... ...

  1. #1
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    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:
    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;
    											
    }
    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 ?

  2. #2
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    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.

  3. #3
    Algorithm Dissector iMalc's Avatar
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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 ?
    If you post the code that calls them it would help.

    Please also read the FAQ entry about Casting malloc.
    My homepage
    Advice: Take only as directed - If symptoms persist, please see your debugger

    Linus Torvalds: "But it clearly is the only right way. The fact that everybody else does it some other way only means that they are wrong"

  4. #4
    Banned master5001's Avatar
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    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.

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