链表

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

#define CMB_OK 0
#define CMB_ERROR 1
#define CMB_SYSTEM_ERROR 2

struct dl_node {
 void *body;
 struct dl_node *next;
 struct dl_node *prev;
};

typedef struct cs_list {
 struct dl_node *head;
 struct dl_node *tail
 int number;
} CS_LIST;

int CS_List_Init(CS_LIST **ptr)
{
 CS_LIST *np;
 if( ptr == NULL)
  return CMB_ERROR;

 np = (CS_LIST *)malloc(sizeof(CS_LIST));
 if( np == NULL)
  return CMB_SYSTEM_ERR;

 np->head = np->tail = NULL;
 np->number = 0;
 *ptr = np;
 return CMB_OK;
}

int CS_List_Append(CS_LSIT **ptr, void *np)
{
 struct dl_node *newnode;
 if( ptr == NULL || np == NULL)
  return CMB_ERROR;
 newnode = (struct dl_node *)malloc(sizeof(struct dl_node));
 if(newnode == NULL)
  return CMB_SYSTEM_ERROR;

 newnode->body = np;
 newnode->next = newnode->prev = NULL;
 if( ptr -> number == 0) {
  ptr->head = ptr->tail = newnode;
  return CMB_OK;
 }
 newnode->prev = ptr->tail;
 ptr ->tail->next = newnode;
 ptr ->tail =newnode;
}

int CS_List_Get(CS_LIST *ptr, size_t at, void **item)
{
 int cnt,half_cnt;
 struct dl_node *wp;
 if(CS_LSIT == NULL || item == NULL)
  return CMB_ERROR;
 if( at <= 0 || at > ptr->number)
  return CMB_ERROR;
 half_cnt = cnt / 2;
 if(at <= half_cnt) {
  cnt = 1;
  wp = ptr->head;
  while(cnt < at) {
   wp = wp->next;
   cnt++;
  }
  *item = wp;
 }
 else {
  cnt = ptr->number;
  wp = ptr->tail;
  while (cnt > at){
   wp = wp->prev;
   cnt--;
  }
  *item = wp;
 }
 return CMB_OK;
}

先保存一下，明天继续写，有没有人给Check一下，有没有改进的方法，感觉有点错误？？？