双链表

问题：在分配空间时，遇到问题

定义一个结构体：

typedef struct dLinkListNode
{
int data;
struct dLinkListNode *prior;
struct dLinkListNode *next;
}*dLinkList,dListNode;

dList=(dLinkList)malloc(sizeof(dListNode));与dList=(dLinkList)malloc(sizeof(dLinkList));是不一样的，即指针和结构体的大小不一样，不要想当然。

指针的问题真的小心，一不小心就出错。

代码：

#include <iostream>
#include <cstdlib>
using namespace std;
 
typedef struct dLinkListNode
{
    int data;
    struct dLinkListNode *prior;
    struct dLinkListNode *next;
}*dLinkList,dListNode;
 
void CreateDlinklist(dLinkList &dList)    //尾插入法建立双链表
{
     dLinkList node;
     int elem;
     dList=(dLinkList)malloc(sizeof(dListNode));
     if(!dList)
     {
         cout<<"allocate fail"<<endl;
     }
     else
     {
     dList->data=0;
     dList->next=NULL;
     dList->prior=NULL;
     }
     cin>>elem;
     while(elem!=EOF)
     {
         node=(dLinkList)malloc(sizeof(dListNode));
         if(!node)
         {
             cout<<"allocate fail"<<endl;
             exit(-1);
         }
         else
         {
       if(dList->next==NULL)
       {
         node->data=elem;
         node->next=dList->next;
         dList->next=node;
         node->prior=dList;
       }
       else
       {
           node->data=elem;
           node->next=dList->next;
           dList->next->prior=node;
           dList->next=node;
           node->prior=dList;
       }
         cin>>elem;
         }
     }
 
}
void insertDNode(dLinkList dList,int elem)
{
    dLinkList node,pre,tempNode;
    node=(dLinkList)malloc(sizeof(dListNode));
    if(node==NULL)
    {
        cout<<"allocate fail"<<endl;
        exit(0);
    }
    else
    {
    node->data=elem;
    node->next=NULL;
    node->prior=NULL;
    }
    pre=dList;
    tempNode=dList->next;
    while(tempNode)
    {
        if(tempNode->data<elem)
        {
            pre=tempNode;
            tempNode=tempNode->next;
            if(tempNode==NULL)
           {
              pre->next=node;
              node->prior=pre;
              node->next=NULL;
           }
        }
        else
        {
            node->next=pre->next;
            pre->next->prior=node;
            pre->next=node;
            node->prior=pre;
            break;
        }
    }
     
         
 
}
 
void deleteDNode(dLinkList dList,int elem)
{
    dLinkList node,pre;
    pre=dList;
    node=dList->next;
    while(node)
    {
        if(node->data==elem)
        {
            pre->next=node->next;
            node->next->prior=pre;
            break;
        }
        else
        {
            pre=node;
            node=node->next;
            if(node==NULL)
            {
                cout<<"there is no the element"<<endl;
            }
        }
    }
}
void display(dLinkList dList)
{
    dLinkList node;
    node=dList->next;
    while(node)
    {
        if(node->next==NULL)
        {
            cout<<node->data;
        }
        else
        {
            cout<<node->data<<"->";
        }
        node=node->next;
    }
    cout<<endl;
}
 
int main()
{
    dLinkList dList;
    cout<<"创建双链表:"<<endl;
    CreateDlinklist(dList);
    cout<<"输出双链表"<<endl;
    display(dList);
 
    deleteDNode(dList,3);
    cout<<"输出双链表"<<endl;
    display(dList);
 
    insertDNode(dList,9);      //插入元素
    cout<<"输出双链表"<<endl;
    display(dList);
    return 0;
}