singly-linked list

List.h

//
//  List.h
//  Data Structures
//
//  Created by Salvador Guerrero on 3/15/16.
//  Copyright © 2016 ByteApps. All rights reserved.
//

/*
 * Singly-linked list
 *
 * A samples can be found at: https://github.com/ObjSal/Data-Structures
 */

#ifndef List_h
#define List_h

// define your own data type before including this file

#ifndef item_type
#define item_type int
#endif

struct list {
    item_type item;     // data
    struct list *next;  // pointer to successor
};


/*
 * recursive search
 */

struct list* list_search(struct list *list_head, item_type item)
{
    if (list_head == NULL) return NULL;

    if (list_head->item == item)
    {
        return list_head;
    }
    else
    {
        return list_search(list_head->next, item);
    }
}

/*
 * insertion done at the beginning of the list instead of traversing all the list
 */

void list_insert(struct list **list_head, item_type item)
{
    struct list *temp_list = (struct list *)malloc(sizeof(struct list));

    temp_list->item = item;
    temp_list->next = *list_head;

    *list_head = temp_list;
}

/*
 * find the predecessor of a given list node
 */

struct list* list_predecessor(struct list *list_head, item_type item)
{
    if (list_head == NULL || list_head->next == NULL)
    {
        printf("Error: predecessor not found\n");
        return NULL;
    }

    if (list_head->next->item == item)
    {
        return list_head;
    }
    else
    {
        return list_predecessor(list_head->next, item);
    }
}

/*
 * delete a node with the given item.
 */

void list_delete(struct list **list_head, item_type item)
{
    struct list *item_list_p = list_search(*list_head, item);
    struct list *predecessor;

    if (item_list_p == NULL) return;

    predecessor = list_predecessor(*list_head, item);

    if (predecessor)
    {
        predecessor->next = item_list_p->next;
    }
    else
    {
        *list_head = item_list_p->next;
    }

    // free node memory

    free(item_list_p);
}

/*
 * prints all the items
 */

void list_description(struct list *list_head)
{
    if (list_head == NULL) return;

    int count = 0;
    for (struct list *list = list_head; list; list = list->next)
    {
        printf("[%d], item = %d\n", ++count, list->item);
    }
}

/*
 * free all the list.
 */

void list_free(struct list *list_head)
{
    if (list_head == NULL) return;

    struct list *list = list_head;

    for (;list;)
    {
        struct list *temp_list = list->next;
        free(list);
        list = temp_list;
    }
}


#endif /* List_h */