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;
}