algorithms: list_ins_next statement outline

list_ins_next_statements.c

/*********************************************
 * EXAMPLE
 *********************************************

Below is an outline of steps for inserting a node into a singly
linked list using method statements.
*/

/* linked-list element structure */
typedef struct ListElmt_ {

    void               *data;
    struct ListElmt_   *next;

} ListElmt;


/* linked list structure */
typedef struct List_ {

    int                size;
    ListElmt           *head;
    ListElmt           *tail;

} List;


// Initial List contains 2 nodes 
List = *L;

    +---------+------+       +---------+------+
    |  SJC    |  * → | →  →  |  LAX    |  *   |
    +---------+------+       +---------+------+          


// demo function
void link_ins_next(List *list, ListElmt *element, const void *data){

    ListElmt *N;

    // declare a (new) pointer var N (point to list nodes)
    // allocate new node, let pointer var N point to it

    N = (ListElmt *)malloc(sizeof(ListElmt));

                     +---------+------+
                     | NULL    |  *   |
                     +---------+------+


    // Copy the data str "SFO" into the airport field of N's referent
    // We could also pass the data in as an input var (i.e. *data)
 
    strcpy(N->Airport, "SFO");

                     +---------+------+
                     |  SFO    |  *   |
                     +---------+------+


    // Change the link field of N's referent to point to the 2nd node of list L

                     +---------+------+
N:                   |  SFO    |  *   |
                     +---------+--↓---+
                                  ↓
                                  ↓
    +---------+------+       +---------+------+
L:  |  SJC    |  *   |       |  LAX    |  *   |
    +---------+------+       +---------+------+          

    N->Link = L->Link;


    // Change the link field of the 1st node of list L to point to N's referent 

                     +---------+------+
                     |  SFO    |  *   |
                     +---------+--↓---+
                      ↗           ↓
                    ↗             ↓
    +---------+---↗--+       +---------+------+
    |  SJC    |  *   |       |  LAX    |  *   |
    +---------+------+       +---------+------+