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Date: Thu, 06 Sep 2012 20:52:16 -0400
From: pete <pfiland@mindspring.com>
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Bill Cunningham wrote:
> 
> pete wrote:
> >
> > /* BEGIN d_append.c */
> > /*
> > ** Demonstration of use of int list functions.
> > */
> > #include <stdio.h>
> > #include <stdlib.h>
> >
> > #define NUMBERS         15,14,13,7,20,9,8,12,11,6
> >
> > #define NMEMB(A)        (sizeof (A) / sizeof *(A))
> >
> > struct d_node {
> >    struct d_node       *next;
> >    int                  data;
> > };
> >
> > typedef struct d_node d_type;
> 
>     Wow if this is simple I'd hate to see complex.
> Whew. One step at a time
> I guess.
> 
> > int d_fprintf(const d_type *node, FILE *stream);
> > d_type *d_append(d_type **head, d_type *tail, int data);
> 
>     I've never worked with pointers to pointers.
> Except in the command line.
> What's head and tail for? 

head points to the first node of the linked list.
tail points to the last node of the linked list.

>I only used next.

What can you do with a linked list, 
by only using next?

I simplified it:

/* BEGIN d_start.c */
/*
** Demonstration of use of int list functions.
** d_start
** d_append_0
*/
#include <stdio.h>
#include <stdlib.h>

#define NUMBERS         15,14,13,7,20,9,8,12,11,6

#define NMEMB(A)        (sizeof (A) / sizeof *(A))

struct d_node {
    struct d_node       *next;
    int                 data;
};

int d_fprintf(const struct d_node *node, FILE *stream);
struct d_node *d_start(int data);
struct d_node *d_append_0(struct d_node *tail, int data);
void d_free(struct d_node *node);

int 
main(void)
{
    struct d_node *head;
    struct d_node *tail;
    int numbers[] = {NUMBERS};
    int *ptr = numbers;
    int *const after = numbers + NMEMB(numbers);

    puts("/* BEGIN d_start.c output */");
    puts("\nOriginal order of list of ints:");
    head = tail = d_start(*ptr);
    if (head != NULL) {
        while (++ptr != after) {
            tail = d_append_0(tail, *ptr);
            if (tail == NULL) {
                puts("malloc trouble!");
                break;
            }
        }
    } else {
        puts("malloc trouble!");
    }
    d_fprintf(head, stdout);
    d_free(head);
    puts("\n/* END d_start.c output */");
    return 0;
}

int 
d_fprintf(const struct d_node *node, FILE *stream)
{
    int rc = 0;
    
    while (node != NULL) {
        if (0 > (rc = fprintf(stream, "%d\n", node -> data))) {
            break;
        }
        node = node -> next; 
    }
    return rc;
}

struct d_node *
d_start(int data)
{
    struct d_node *node;

    node = malloc(sizeof *node);
    if (node != NULL) {
        node -> next = NULL;
        node -> data = data;
    }
    return node;
}

struct d_node *
d_append_0(struct d_node *tail, int data)
{
    struct d_node *node;

    node = malloc(sizeof *node);
    if (node != NULL) {
        node -> next = NULL;
        node -> data = data;
        tail -> next = node; 
    }
    return node;
}

void 
d_free(struct d_node *node)
{
    struct d_node *next_node;

    while (node != NULL) {
        next_node = node -> next;
        free(node);
        node = next_node;
    }
}

/* END d_start.c */



-- 
pete