Data structure---C-language implementation of two-way linked list operations

#include <stdio.h> #include <stdlib.h> typedef int ELEMTYPE;TYPEDEF struct Doublelinkedlist {Elemtyp       e data;       struct Doublelinkedlist *pre;  struct Doublelinkedlist *next;     }dlinkedlist_node;     Establish linked list dlinkedlist_node* Create_dlink () {Dlinkedlist_node *head,*p,*s;     int x;     Head = (dlinkedlist_node*) malloc (sizeof (Dlinkedlist_node));     p = head;         while (1) {printf ("Please enter the node to be saved, end with 0 input: \ n");       scanf ("%d", &x);            if (x! = 0) {s = (dlinkedlist_node*) malloc (sizeof (Dlinkedlist_node));            s->data = x;            s-> pre = P;            P->next = s;         P=s;            } else {printf ("\ n data input end \ n");         Break      }} p->next = NULL;      Head = Head->next;      Head->pre = NULL;  return head;      }//sequential, reverse order Print List void Print_dlink (Dlinkedlist_node *head) {Dlinkedlist_node *p,*s;      p = head; printf ("In the positive order output doubly linked listNode: \ n ");          while (p) {printf ("%d", p->data);          s = p;      p = p->next;      } printf ("\ n reverse output a node in a doubly linked list: \ n");          while (s) {printf ("%d", s->data);      s = s->pre;  } printf ("\ n \ n"); }//Delete node of the specified element dlinkedlist_node* delete_dlinkedlist_node (Dlinkedlist_node *head,int i) {Dlinkedlist_node *p      ;      p = head;          if (P->data = = i) {head = p->next;          Head->pre = NULL;          Free (p);      return head;              } while (p) {if (P->data = = i) {P->pre->next = p->next;              P->next->pre = p->pre;              Free (p);           return head;       } p = p->next; } printf ("Sorry for the wrong input data!")       , did not find the data you want to delete \ n ");   return head;     }//Insert a node dlinkedlist_node* insert_dlinkedlist_node (Dlinkedlist_node *head,int i) {Dlinkedlist_node *p,*temp;     p = head; temp = (dlinkedlist_node*) malloc (sizeof (Dlinkedlist_node));     Temp->data = i;         if (I < p->data)//smaller than the head node data, inserted into the list head {head = temp;         Head->next = p;//Here P is the original head head->pre = NULL;      P->pre = head;//Here P is the original head return head;      } while (P! = NULL && i > P->data)//Find the appropriate insertion position {p = p->next;          if (I < p->data)//Find the appropriate insertion position in the middle of the list {temp->next = p;          Temp->pre = p->pre;          P->pre->next = temp;          P->pre = temp;       return head;  } else//did not find a suitable location, only inserting data into the list trailing {p->next = temp;           Traverse to the tail of the list, P==null temp->pre = p;           Temp->next = NULL;        return head;      }} int main () {Dlinkedlist_node *head;      Head = Create_dlink ();      Print_dlink (head);   return 0;}

Data structure---C-language implementation of two-way linked list operations