双向循环链表并保存--C语言实现

         用双向循环链表来保存一些并不是很大的量的数据，不失为一种有效方便的方法。可以用在书签、历史记录等场所。

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

//exit -1 file operation error, -2 memory error,

struct labelInfo{
    int id;
    char name[20]; //data domain
};

/***
    struct: double linked list.
***/
typedef struct node{
    struct node *llink; //left link domain
    struct node *rlink; //right link domain
    struct labelInfo *myInfo;
}DLINKLIST;


/***
    create: double linked list.
    return: a pointer point to a double linked list.
***/
DLINKLIST *DLinkList_createList(void)
{
    DLINKLIST *pDLinkList;

    if((pDLinkList=(DLINKLIST *)malloc(sizeof(DLINKLIST)))==NULL){
        fprintf(stderr,"error:can't allocate memery!\n");
        return NULL;
    }
    fprintf(stdout,"input name 1:create a new list.\n");
    (pDLinkList->myInfo)=NULL; //data domain
         /*................*/
    pDLinkList->llink=pDLinkList;
    pDLinkList->rlink=pDLinkList;
    return pDLinkList;
}

/***
    NewNode: create a new node of double linked list.
***/
DLINKLIST *DLinkList_newNode(DLINKLIST *list,struct labelInfo *info)
{
    DLINKLIST *pDLinkList,*cDLinkList;

    pDLinkList=list->llink; //point to last node
    if((cDLinkList=(DLINKLIST *)malloc(sizeof(DLINKLIST)))==NULL){
        fprintf(stderr,"error:can't allocate memery!\n");
        exit -2;
    }
    fprintf(stdout,"input name 1:create a new node.\n");
    cDLinkList->myInfo=info; //data domain
         /*................*/
    cDLinkList->llink=pDLinkList; //point to last node
    cDLinkList->rlink=list; //point head node
    pDLinkList->rlink=cDLinkList; //add a new node
    list->llink=cDLinkList;

    return list;
}


/***
    DLinkList_searchNode: search a node of double linked list.
***/
DLINKLIST *DLinkList_searchNode(DLINKLIST *list,int id)
{
    int myId;
    DLINKLIST *pDLinkList;

    pDLinkList=list->rlink;
    while(pDLinkList!=list){
        myId=pDLinkList->myInfo->id;
        if(myId==id)
            return pDLinkList;
        else pDLinkList=pDLinkList->rlink;
    }
    fprintf(stderr,"info:can't find %d\n",id);
    return NULL;
}
/***
    DLinkList_deleteNode: delete a node of double linked list.
***/
void DLinkList_deleteNode(DLINKLIST *delNode)
{

    DLINKLIST *pDLinkList;

    pDLinkList=delNode->rlink;
    pDLinkList->llink=delNode->llink;
    delNode->llink->rlink=pDLinkList;
    free(delNode->myInfo);
    free(delNode);
}


/***
    DLinkList_newInfo: create a new info struct.
***/
struct labelInfo* DLinkList_newInfo(int id)
{
    struct labelInfo *ptr;

    if((ptr=(struct labelInfo *)malloc(sizeof(struct labelInfo)))==NULL){
        fprintf(stderr,"error:can't allocate node memery!\n");
        exit -2;
    }
    ptr->id=id;
    fprintf(stdout,"please input a name.\n");
    scanf("%s",ptr->name);

    return ptr;
}

/***
    DLinkList_print: print double linked list.
***/
void DLinkList_print(DLINKLIST *list)
{
    int n;
    DLINKLIST *pDLinkList;

    pDLinkList=list->rlink;
    fprintf(stdout,"result: \n");
    while(pDLinkList!=list){
        fprintf(stdout,"id: %d    name:%s\n",pDLinkList->myInfo->id,pDLinkList->myInfo->name);
        pDLinkList=pDLinkList->rlink;
    }
    fprintf(stdout,"\n");
}
/***
    DLinkList_save: save double linked list.
***/
int DLinkList_save(DLINKLIST *list)
{
    FILE *fp;
    DLINKLIST *pDLinkList;

    if((fp=fopen("splay_label","w"))==NULL){
        fprintf(stderr,"error:can't open the file of splay_lalel!");
        return -1;
    }
    fwrite(list,sizeof(DLINKLIST),1,fp); //save first node
    fwrite(list->myInfo,sizeof(struct labelInfo),1,fp); //save lable struct
     pDLinkList=list->llink;
    while(pDLinkList!=list){
        fwrite(pDLinkList,sizeof(DLINKLIST),1,fp);
        fwrite(pDLinkList->myInfo,sizeof(struct labelInfo),1,fp); //save lable struct
        pDLinkList=pDLinkList->llink;
    }
    fclose(fp);
    return 0;
}
/***
    DLinkList_read: read double linked list.
    return : -1 can't find the file.
***/
DLINKLIST *DLinkList_read(DLINKLIST *list)
{
    FILE *fp;
    DLINKLIST *pDLinkList,*cDLinkList;
    int of=0;

    if((fp=fopen("splay_label","r"))==NULL){
        fprintf(stderr,"error:can't open the file of splay_lalel!\n");
        return NULL;
    }

    if((list=(DLINKLIST *)malloc(sizeof(DLINKLIST)))==NULL){
        fprintf(stderr,"error:can't allocate memery!\n");
        return NULL;
    }

    fread(list,sizeof(DLINKLIST),1,fp); //read first node
    list->rlink=NULL;
    list->llink=NULL;
    list->myInfo=NULL;
    pDLinkList=list; //

    while((of=feof(fp))==0){
        if((cDLinkList=(DLINKLIST *)malloc(sizeof(DLINKLIST)))==NULL){
            fprintf(stderr,"error:can't allocate memery!\n");
            return NULL;
        }
        pDLinkList->llink=cDLinkList; //link next node
        if(fread(cDLinkList,sizeof(DLINKLIST),1,fp)!=1){
            free(cDLinkList);
            break;
        }
        cDLinkList->rlink=pDLinkList;
        cDLinkList->llink=NULL;
        pDLinkList=cDLinkList;
        if((cDLinkList->myInfo=(struct labelInfo*)malloc(sizeof(struct labelInfo)))==NULL){
            fprintf(stderr,"error:can't allocate memery!\n");
            return NULL;
        }
        if(fread(cDLinkList->myInfo,sizeof(struct labelInfo),1,fp)!=1){
            free(cDLinkList->myInfo);
            break;
        }
    }
    list->rlink=pDLinkList;
    pDLinkList->llink=list;
    fclose(fp);
    return list;
}

int main(int argc, char *argv[])
{
    DLINKLIST *list,*delNode;
    struct labelInfo *ptr;
    int n;

    if((list=DLinkList_read(list))==NULL){
        if((list=DLinkList_createList())==NULL){ //create node
            fprintf(stderr,"error:can't ceate a list.\n");
            return -1;
        }
    }
    ptr=DLinkList_newInfo(1);
    list=DLinkList_newNode(list,ptr);

    ptr=DLinkList_newInfo(2);
    list=DLinkList_newNode(list,ptr);

    ptr=DLinkList_newInfo(3);
    list=DLinkList_newNode(list,ptr);

    DLinkList_print(list);
    fprintf(stdout,"Id 2 name:%s\n",DLinkList_searchNode(list,2)->myInfo->name);

    fprintf(stdout,"Delete: please input the id .\n");
    scanf("%d",&n);
    delNode=DLinkList_searchNode(list,n);
    if(delNode==NULL)
        fprintf(stderr,"Error: not find this ID!\n");
    else
        DLinkList_deleteNode(delNode);
    DLinkList_print(list);

    ptr=DLinkList_newInfo(3);
    list=DLinkList_newNode(list,ptr);
    DLinkList_print(list);

    DLinkList_save(list);     //save


    return 0;
}