C语言---双向链表的插入、删除、查找操作

/*
 *程序功能：对双向链表操作，主要包括：插入结点、删除结点、查找结点等基本操作
 *需要注意的是，链表中附加了一个结点root_p
 *root_p是链表的根节点，root_p中的data字段存储的是当前链表中的总结点个数
 *root_p->prev指向链表中第一个存放数据的结点，root_p->next指向链表中最后一个存放数据的结点；
 *当链表为空时，root_p->prev和root_p->next都为NULL
*/

#include
#include

struct node
{
	struct node *prev;   /*指向前一个结点的指针*/
	int data;
	struct node *next;   /*指向后一个结点的指针*/
};

int dll_insert(struct node *root_p, int value);  /*插入结点，插入成功返回1，否则返回0*/
int dll_delete(struct node *root_p, int value);  /*删除结点，插入成功返回1，否则返回0*/
int dll_member(struct node *root_p, int value);  /*查找结点，如果存在返回1，否则返回0*/
void dll_print(struct node *root_p);  /*打印链表*/

int main(int argc, char **argv)
{
	struct node *root_p;
	int i;
	
	/*root_p是链表的根节点，但是它并不存储链表的有效结点，root_p中的data存储的是当前链表中的总结点个数
	**root_p->prev指向链表中第一个存放数据的结点，root_p->next指向链表中最后一个存放数据的结点
	*/
	root_p = malloc( sizeof(struct node) );    
	root_p->prev = root_p->next = NULL;
	root_p->data = 0;

	srand(5);
	printf("insert...\n");
	for(i=0; i<3; i++) dll_insert(root_p, rand()%100);
	dll_print(root_p);
	
	printf("\nmember...\n");
	printf("10?exist : %d\n", dll_member(root_p,10));
	printf("65?exist : %d\n", dll_member(root_p,65));
	printf("75?exist : %d\n", dll_member(root_p,75));
	printf("9?exist : %d\n", dll_member(root_p,9));
	printf("70?exist : %d\n", dll_member(root_p,70));
	printf("100?exist : %d\n", dll_member(root_p,100));
	
	printf("\ndelete\n");
	dll_delete(root_p,10);
	dll_delete(root_p,65);
	dll_delete(root_p,75);
	dll_delete(root_p,9);
	dll_delete(root_p,70);
	dll_delete(root_p,100);
	dll_print(root_p);
	
	return 0;
}

int dll_insert(struct node *root_p, int value)
{
	struct node *save_p, *curr_p;
	struct node *new_p;
	
	save_p = NULL;
	curr_p = root_p->prev;
	while(curr_p!=NULL && curr_p->datanext;
		
	if(curr_p!=NULL && curr_p->data == value)return 0;
	if( (new_p=malloc(sizeof(struct node))) == NULL)return 0;
	new_p->data = value;
	
	if(curr_p != NULL) save_p = curr_p->prev;
	else if(root_p->data != 0) save_p = root_p->next;
	
	new_p->next = curr_p;
	new_p->prev = save_p;
	
	if(save_p == NULL) root_p->prev = new_p;
	else save_p->next = new_p;
	if(curr_p == NULL) root_p->next = new_p;
	else curr_p->prev = new_p;
	
	root_p->data++;
	return 1;
}

int dll_delete(struct node *root_p, int value)
{
	struct node *save_p, *curr_p, *next_p;
	
	curr_p = root_p->prev;
	while(curr_p!= NULL && curr_p->datanext;
		
	if(curr_p!=NULL && curr_p->data==value)
	{
		save_p = curr_p->prev;
		next_p = curr_p->next;
		if(save_p != NULL) save_p->next = next_p;
		else root_p->prev = next_p;
		if(next_p != NULL) next_p->prev = save_p;
		else root_p->next = save_p;
		root_p->data--;
	}
	else return 0;  /* 空链表 或者 没有找到要删除的内容*/
}

int dll_member(struct node *root_p, int value)
{
	struct node *curr_p = root_p->prev;
	
	while(curr_p!=NULL && curr_p->datanext;
		
	if(curr_p!=NULL && curr_p->data==value) return 1;
	else return 0;
}

void dll_print(struct node *root_p)
{
	struct node *curr_p = root_p->prev;
	printf("total number of nodes = %d .\n", root_p->data);
	while(curr_p != NULL)
	{
		printf("%d  ",curr_p->data);
		curr_p = curr_p->next;
	}
	
	printf("\n");
}