scrappy - was reading Joel on Software, and wrote this in relation to an interview question in there - "how we you reverse a linked list?"

reverse_list.c

#include <stdio.h>
#include <string.h>
#include <stdlib.h>

// linked list
//
typedef struct sweary sweary;
struct sweary {
    char wurd[64];
    sweary *next;
};

// stack /////////////////////////////////////////////////

typedef struct stack stack;
typedef struct stackitem stackitem;

struct stack {
    int count;
    void *head;
};

struct stackitem {
    void *item;
    stackitem *next;
};

stack *new_stack()
{
    printf("NEW STACK!\n");
    stack *s = calloc(1, sizeof(stack));
    s->count = 0;

    return s;
}

void stack_push(stack* s, void *item)
{
    stackitem *si = calloc(1, sizeof(stackitem));
    si->item = item;

    if (s->count == 0) {
        s->head = si;
    }
    else {
        si->next = s->head;
        s->head = si;
    }
    s->count++;
}

void *stack_pop(stack *s)
{
    if (s->count == 0)
        return NULL;
    stackitem *item = s->head;
    void *goods = item->item;
    if (item->next != NULL) {
        s->head = item->next;
    } else {
        s->head = NULL;
    }
    free(item);
    s->count--;
    return goods;
}

// end stack ////////////////////////////////////////////

sweary *new_swearwurd(char *wurd)
{
    if (strlen(wurd) > 63) {
        printf("Git tae fock\n");
        return NULL;
    }
    sweary *w = calloc(1, sizeof(sweary));
    strcpy(w->wurd, wurd);
    w->next = NULL;

    return w;
}

void add_swearwurd(sweary *list, char *wurd)
{
    if (  (list == NULL)
       || (strlen(wurd) > 63)) {
        printf("Git tae fock\n");
        return;
    }
    sweary *current;
    current = list; // head of list
    while (current->next != NULL)
        current = current->next;

    sweary *new = new_swearwurd(wurd);
    current->next = new;
}

///////////////////////////////////////////////////////////////////
// LIST Ops

void print_list(sweary *list)
{
    sweary *current;
    current = list;
    while (current->next != NULL)
    {
        printf("%s!\n", current->wurd);
        current = current->next;
    }
    printf("%s!\n\n", current->wurd);
}

sweary *reverse_list(sweary *list)
{
    // assert list > 1 yada yada
    stack *s = new_stack();
    sweary *current;
    current = list;

    sweary *last_head = current; // save ptr to current head - it'll be the last in the reversed list

    while (1)
    {
        stack_push(s, current);
        current = current->next;
        if (current->next == NULL)
        {
            stack_push(s, current);
            break;
        }
    }

    // REeeeeeeeeewind! ////////////////////////////////////////////////////////////////

    sweary *newlist = stack_pop(s); // we'll return this as pointer to head

    sweary *next;   // these two change as we iterate through list
    sweary *curnew; //

    curnew = newlist;

    while (1)
    {
        next = stack_pop(s);
        curnew->next = next;
        curnew = next;
        if (curnew == last_head)
        {
            curnew->next = NULL;
            break;
        }
    }
    return newlist;
}

int main()
{
    sweary *sw_list = new_swearwurd("jobbie");
    add_swearwurd(sw_list, "boabie");
    add_swearwurd(sw_list, "boobie");
    add_swearwurd(sw_list, "patootie");

    print_list(sw_list);

    sweary *rev = reverse_list(sw_list);
    print_list(rev);

}