insert_node

#include <stdio.h>#include <stdlib.h>#include <string.h>typedef struct ListNode{char *data;ListNode *pre;ListNode *next;}ListNode;void insert_node(ListNode *head,char *str) {ListNode *p, *q;p = head;q = (ListNode*)malloc(sizeof(ListNode));q->data = (char*)malloc(strlen(str) + 1);strcpy(q->data,str);while (strcmp(str,p->data) >= 0)//insert before node p{if (0 == strcmp(str,p->data)){return;}p = p->next;if (NULL == p->next){break;}}if (NULL == p->next){if (strcmp(str,p->data) >= 0){q->next = NULL;q->pre  = p;p->next = q;}}q ->next = p;q->pre = p->pre;p->pre->next = q;p->pre = q;}int main(){ListNode *head;getchar();return 0;}