在循环单链表的开头插入一个节点(参考实现)：

#include<stdio.h>  
#include<stdlib.h>  
void beg_insert(int);  
struct node  
{  
    int data;  
    struct node *next;  
};  
struct node *head;  
void main ()  
{  
    int choice,item;  
    do   
    {  
        printf("\nEnter the item which you want to insert?\n");  
        scanf("%d",&item);  
        beg_insert(item);  
        printf("\nPress 0 to insert more ?\n");  
        scanf("%d",&choice);  
    }while(choice == 0);  
}  
void beg_insert(int item)    
{    

    struct node *ptr = (struct node *)malloc(sizeof(struct node));    
    struct node *temp;  
    if(ptr == NULL)    
    {    
        printf("\nOVERFLOW");    
    }    
    else     
    {    
        ptr -> data = item;    
        if(head == NULL)    
        {    
            head = ptr;    
            ptr -> next = head;    
        }    
        else     
        {       
            temp = head;    
            while(temp->next != head)    
                temp = temp->next;    
            ptr->next = head;     
            temp -> next = ptr;     
            head = ptr;    
        }     
    printf("\nNode Inserted\n");  
    }    
}