循环链表可以用来使计算机处理内存工作区或输出至数据缓冲区。
循环链表的插入和删除
#include " iostream "
#include " stdlib.h "
using namespace std;
struct clist
{
int data;
struct clist * next;
};
typedef struct clist cnode;
typedef cnode * clink;
/* -----循环链表的输出------ */
void printclist( clink head)
{
clink ptr;
head = head -> next;
ptr = head;
do
{
printf( " [%d] " ,ptr -> data);
ptr = ptr -> next;
} while (head != ptr && head != head -> next);
printf( " \n " );
}
/* -----循环链表的结点插入---- */
clink insertnode(clink head,clink ptr, int value)
{
clink new_node;
new_node = (clink) malloc( sizeof (cnode));
if ( ! new_node)
return NULL;
new_node -> data = value;
new_node -> next = NULL;
if (head == NULL)
{
new_node -> next = new_node;
return new_node;
}
if (ptr == NULL)
{
/* ----情况1：插在第一结点之前--- */
new_node -> next = head -> next;
head -> next -> next = new_node;
}
else
{
/* -----情况2：插在结点之后------- */
new_node -> next = ptr -> next;
ptr -> next = new_node;
}
if (ptr == head)
head = new_node;
return head;
}
/* ---循环链表结点删除--- */
clink deletenode(clink head,clink ptr)
{
clink previous;
if (head == NULL)
{
/* ----情况1：删除第一个结点---- */
head -> next = ptr -> next;
}
else
{
/* --情况2：删除中间结点--- */
previous = head;
if (head != head -> next)
while (previous -> next != ptr)
previous = previous -> next;
previous -> next = ptr -> next;
}
if (ptr == head)
head = previous;
free(ptr);
return head;
}
/* 使用插入结点的方式来创建链表，完成后将链表内容输出，然后删除前后两结点 */
int main()
{
clink head = NULL;
int list[ 6 ] = { 9 , 7 , 3 , 4 , 5 , 6 };
int i;
head = insertnode(head,head,list[ 0 ]);
printf( " 创建第一个结点： " );
printclist(head);
/* ---情况1：插在第一结点前---- */
head = insertnode(head,NULL,list[ 1 ]);
printf( " 插入第一结点之前： " );
printclist(head);
for (i = 2 ;i < 6 ;i ++ )
{
/* ---情况2:插在结点之后----- */
head = insertnode(head,head -> next,list[i]);
printf( " 插入结点之后： " );
printclist(head);
}
/* ---情况1：删除第一个结点--- */
head = deletenode(head,head -> next);
printf( " 删除第一个结点： " );
printclist(head);
/* --删除最后一个结点-- */
printf( " 删除最后一个结点： " );
head = deletenode(head,head);
printclist(head);
}
转载于:https://my.oschina.net/garyun/blog/602945