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/*
* Copyright (c) Carlos Maiolino <[email protected]>.
* All Rights Reserved.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it would be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
/* This is a simple example of double linked lists I wrote for fun
* Because I had nothing better to do :)
*/
#include <stdio.h>
#include <stdlib.h>
struct list_item {
int key;
struct list_item *prev;
struct list_item *next;
};
struct list_item *list_add(struct list_item *HEAD, int key)
{
struct list_item *item = malloc(sizeof(struct list_item));
if (!item)
goto err_out;
item->key = key;
item->prev = NULL;
/* list is empty, just asign this item as HEAD */
if (!HEAD) {
item->next = NULL;
HEAD = item;
return HEAD;
}
item->next = HEAD;
HEAD->prev = item;
HEAD = item;
return HEAD;
err_out:
return NULL;
}
void list_del_by_item(struct list_item **HEAD, int i)
{
struct list_item *item = *HEAD;
for (; i > 0; i--) {
if (item) {
item = item->next;
} else {
printf("Can't free an inexistent item\n");
return;
}
}
/* if this is the last item, item->next is already NULL */
if (item->prev)
item->prev->next = item->next;
else {
*HEAD = item->next;
}
if (item->next)
item->next->prev = item->prev;
free(item);
return;
}
/*
int list_del_by_key(list, key)
int list_search(list, key)
*/
void print_list(struct list_item *HEAD)
{
struct list_item *iter = HEAD;
if (!HEAD) {
printf("List is empty\n");
return;
}
if (HEAD->prev != NULL) {
printf("Item is not the head of the list\n");
return;
}
while (iter) {
printf(" %d", iter->key);
iter = iter->next;
}
printf("\nEND OF LIST\n");
}
void print_node(struct list_item *item)
{
int *val = &(item->key);
printf("NODE= %p \n", item);
printf(" .prev = %p\n", item->prev);
printf(" .next = %p\n", item->next);
printf(" .key = %p\n", &(item->key));
printf(" .key = %d\n", *(&(item->key)));
printf(" .key = %d\n", *val);
}
void debug_list(struct list_item *HEAD)
{
while (HEAD) {
print_node(HEAD);
HEAD = HEAD->next;
}
}
int main(void)
{
/* Init list head */
struct list_item *HEAD = NULL;
int val;
char cmd;
while (1) {
printf("Select option: ");
scanf(" %c", &cmd);
switch (cmd) {
case 'a':
printf("Add value: ");
scanf(" %d", &val);
HEAD = list_add(HEAD, val);
break;
case 'd':
printf("Item to delete (starting on 0): ");
scanf(" %d", &val);
if (HEAD)
list_del_by_item(&HEAD, val);
else
printf("List is empty\n");
break;
case 'p':
print_list(HEAD);
break;
case 'D':
debug_list(HEAD);
break;
case 'q':
goto out;
default:
printf("a: add to list, d: del item, p: print\n");
break;
}
}
out:
while (HEAD) {
struct list_item *next = HEAD->next;
free(HEAD);
HEAD = next;
}
return 0;
}
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