双链表基本操作

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

typedef struct node
{
struct node *pre;
struct node *next;
int data;
char *name;
}Node;

#define LEN (sizeof(Node))

/******************************************************************************************
*函数名称：Node* create_double_link(int n)
*函数功能：创建升序排列的双链表
*入口参数：链表节点个数
*返 回 值：指向节点(结构体)的指针
*******************************************************************************************/
Node* create_double_link(int n)
{
Node *current;
Node *head;
Node *new;
int i;

new = (Node*)malloc(LEN*n);
if(NULL == new)
{
return NULL;
}

for(i = 0; i < n; i++)
{
new->data = (i+1)*2;
/*如果是头结点，要赋值给head，用于返回*/
if(0 == i)
{
new->name = "head";
new->pre = NULL;
head = new;
/*头结点不用current->next = new;*/
current = new;
new++;
}
/*如果是尾节点*/
else if((n-1) == i)
{
new->name = "tail";
new->pre = current;

/*开始写成current->next = NULL，导致没有尾节点;*/
{
current->next = new;
new->next = NULL;
}

/*尾节点不用current = new;*/
/*尾节点不用new++;*/
}
/*中间节点，实际上相当于在双链表的尾部插入新节点*/
else
{
new->name = "body";
new->pre = current;
current->next = new;
current = new;
new++;
}
}
/*头结点的前驱是空*/
head->pre = NULL;

return head;
}

/******************************************************************************************
*函数名称：int insert_double_link(Node **linkp, int data, char *name)
*函数功能：创建往升序排列的双链表中插入新的节点
*入口参数：linkp, 指向链表头节点的指针的指针; data, 新节点的数值字段; name, 新节点的名称字段
*返 回 值：-1, 内存申请失败; 1, 插入成功
*******************************************************************************************/
int insert_double_link(Node **linkp, int data, char *name)
{
Node *current;
Node *new;

while((current = *linkp) != NULL && current->data < data)
{
linkp = ¤t->next;
}

new = (Node*)malloc(LEN);
/*如果申请内存失败，返回-1*/
if(new ==  NULL)
{
return -1;
}
new->data = data;
new->name = name;

/*不是尾节点*/
if(current != NULL)
{
new->pre = current->pre;
current->pre = new;
}
new->next = current;
*linkp = new;

return 1;
}

/******************************************************************************************
*函数名称：int delete_double_link(Node**p, int data)
*函数功能：删除升序排列的双链表中的节点
*入口参数：p, 指向链表头节点的指针的指针; data, 所删除节点的数值字段;
*返 回 值：-1, 内存申请失败; 1, 插入成功
*******************************************************************************************/
int delete_double_link(Node**p, int data)
{
Node *q;
q = *p;

while(q->data != data )/*相当不解的是while((q->data != data) && (q != NULL))当data值不在链表中时就出错*/
{
q = q->next;
if (q == NULL)
break;
}
/*所要删除的值不在链表中，返回0*/
if(q == NULL)
{
return 0;
}
#if 1
if(*p == q)
{
*p = (*p)->next ;
(*p)->pre = NULL;

}
else if(q->next == NULL)
{
q->pre->next =NULL;
//free(q);
}
else
{
q->pre->next = q->next;
q->next->pre = q->pre ;
}

return 1;
#endif
}

int main()
{
Node *p, *p2;

p = create_double_link(3);
insert_double_link(&p, 1, "body");
p2 = p;
while(p != NULL)
{
printf("The node's name is %s, and data is %d/n", p->name, p->data);
p = p->next;
}
delete_double_link(&p2, 1);
while(p2 != NULL)
{
printf("The node's name is %s, and data is %d/n", p2->name, p2->data);
p2 = p2->next;
}
return 0;
}