I am getting an error message that I think is a problem with gcc, not the code itself. Thanks.
Code:
/usr/lib/gcc/x86_64-linux-gnu/4.6/../../../x86_64-linux-gnu/crt1.o||In function `_start':|
(.text+0x20)||undefined reference to `main'|
||=== Build finished: 1 errors, 0 warnings ===|
Code:
#include <stdio.h>
#include <string.h>
#include "list.h"
void list_init(List *list, void (*destroy) (void *data))
{
// Initialise the list.
list->size = 0;
list->destroy = destroy;
list->head = NULL;
list->tail = NULL;
return ;
}
void list_destroy(List *list)
{
void *data;
// remove each element.
while (list_size(list) > 0)
{
if (list_rem_next(list, NULL, (void **)&data) == 0 && list->destroy != NULL)
{
// Cal a user-defined function to free dynamically allocated data.
list->destroy(data);
}
}
// No operations are allowed now, but clear the structure as a precaution.
memset(list, 0, sizeof(List));
return ;
}
int lists_ins_next(List *list, ListElmt *element, const void *data)
{
ListElmt *new_element;
// Allocate storage for the element.
if ((new_element = (ListElmt *)malloc(sizeof(ListElmt))) == NULL)
{
return -1;
}
// insert the element into the list
new_element->data = (void *)data;
if(element == NULL)
{
// Handle insertion at the head of the list.
if(list_size(list) == 0)
{
list->tail = new_element;
}
new_element->next = list->head;
list->head = new_element;
}
else
{
// Handle insertion somewhere other than at the head;
if(element->next == NULL)
{
list->tail = new_element;
}
new_element->next = element->next;
element->next = new_element;
}
// Adjust the size of the list to account for the inserted element.
list->size++;
return 0;
}
int list_rem_next(List *list, ListElmt *element, void **data)
{
ListElmt *old_element;
// Do not allow removal from an empty list.
if(list_size(list) == 0)
{
return -1;
}
// Remove the element from the list.
if(element == NULL)
{
// Handle removal from the head of the list.
*data = list->head->data;
old_element = list->head;
list->head = list->head->next;
if(list_size(list) == 1)
{
list->tail = NULL;
}
}
else
{
// Handle removal from somewhere other than the head.
if(element->next == NULL)
{
return -1;
}
*data = element->next->data;
old_element = element->next;
element->next = element->next->next;
if(element->next == NULL)
{
list->tail = element;
}
}
free(old_element);
// Adjust the size of the list to account for the removed element.
list->size--;
return 0;
}
list.h
Code:
#ifndef LIST_H
#define LIST_H
#include <stdlib.h>
// Define a structure for linked list elements.
typedef struct ListElmt_ {
void *data;
struct ListElmt_ *next;
} ListElmt;
// Define a structure for linked lists.
typedef struct List_ {
int size;
int (*match)(const void *key1, const void *key2);
void (*destroy)(void *data);
ListElmt *head;
ListElmt *tail;
} List;
void list_init(List *list, void (*destroy)(void *data));
void list_destroy(List *list);
int list_ins_next(List *list, ListElmt *element, const void *data);
int list_rem_next(List *list, ListElmt *element, void **data);
#define list_size(list) ((list)->size)
#define list_head(list) ((list)->head)
#define list_tail(list) ((list)->tail)
#define list_is_head(list, element) ((element) == (list)->head ? 1 : 0)
#define list_is_tail(element) ((element)->next == NULL ? ! : 0)
#define list_data(element) ((element)->data)
#define list_next(element) ((element)->next)
#endif