书上的代码总觉得有点问题

#include <stdio.h>
#include <stdlib.h>
struct link *AppendNopde(struct link *head);
void DisplyNode(struct link *head);
void DeleteMemory(struct link *head);
struct link
{
    int data ;
    struct link *next;
};
int main()
{
    int i=0;
    char x;
    struct link *head = NULL;
    printf("Do you want to append a new node ?\n");
    scanf("%c",&x);
    while(x=='y')
    {
        head = AppendNopde(head);
        DisplyNode(head);
        printf("Do you want to append a new node ?\n");
        scanf("%c",&x);
        ++i;
    }
    printf("%d new nodes had been appended \n",i);
    DeleteMemory(head);
    return 0;
}
struct link *AppendNopde(struct link *head)
{
    struct link *p = NULL,*pr = head;
    int data;
    p = (struct link *)malloc(sizeof(struct link));
    if (p==NULL)
    {
        printf("No enough memory to \n");
        exit(0);
        /* code */
    }
    if (head==NULL)
    {
        head = p;
        /* code */
    }
    else
    {
        while(pr->next!=NULL)
            pr=pr->next;
        pr->next=p;
    }
    printf("Input node data:\n");
    scanf("%d",&data);
    p->data = data;
    p->next = NULL;
    return head;
}
void DisplyNode(struct link*head)
{
    struct link *p = head;
    int j =1;
    while (p!=NULL)
    {
        printf("%5d%10d\n",j,p->data);
        p = p->next;
        ++j;
    }
}
void DeleteMemory(struct link *head)
{
    struct link *p = head ,*pr = NULL;
    while (p!=NULL)
    {
        pr = p;
        p = p->next;
        free(pr);
    }
}