为什么运行结果不是123451234512345

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


typedef struct twoNode {
    int data;
    twoNode* prior;
    twoNode* next;
}DNode;


DNode* CreateNode(int i) {
    DNode* node = (DNode*)malloc(sizeof(DNode));
    node->prior = NULL;
    node->next = NULL;
    node->data = i;
    return node;
}

void InsertFive(DNode* h){
    for (int i = 1; i <= 5; i++) {
        DNode* NewNode = CreateNode(i);
        h->next = NewNode;
        h = h->next;
    }
}

void OutPut(DNode* h) {
    h = h->next;
    while (h)
    {
        if (h == NULL)
            break;
        printf("%d", h->data);
        printf("\n");
        h = h->next;
    }
}



int main() {
    DNode* head = (DNode*)malloc(sizeof(DNode));
    DNode*  h = head;
    InsertFive(h);
    InsertFive(h);
    InsertFive(h);
    OutPut(head);
}

运行结果

肯定不对啊，h指针并没有改变位置，你应该插入5个元素前，将h移动到链表尾部节点才是正确的。不然每次h都是头节点，你插入的是头节点之后，但原先的链表就断掉了。
修改如下：（修改处已增加注释）

#include <stdio.h>
#include<stdlib.h>
 
 
typedef struct twoNode {
    int data;
    twoNode* prior;
    twoNode* next;
}DNode;
 
 
DNode* CreateNode(int i) {
    DNode* node = (DNode*)malloc(sizeof(DNode));
    node->prior = NULL;
    node->next = NULL;
    node->data = i;
    return node;
}
 
void InsertFive(DNode* h){
    while(h->next != NULL) //每次插入节点时，先将h指向最后一个节点
        h = h->next;
    for (int i = 1; i <= 5; i++) {
        DNode* NewNode = CreateNode(i);
        h->next = NewNode;
        h = h->next;
    }
}
 
void OutPut(DNode* h) {
    h = h->next;
    while (h)
    {
        if (h == NULL)
            break;
        printf("%d", h->data);
        printf("\n");
        h = h->next;
    }
}
 
 
 
int main() {
    DNode* head = (DNode*)malloc(sizeof(DNode));
    DNode*  h = head;
    h->next = NULL;   //要初始化头节点的next和prior为空
    h->prior = NULL;
    InsertFive(h);
    InsertFive(h);
    InsertFive(h);
    OutPut(head);
    return 0;
}

void InsertFive(DNode*& h)

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