#include"stdio.h"
#include"malloc.h"
typedef struct node
{
    int data;
    struct node *next;
}NODE;

NODE create_cir();
NODE *connect(NODE *head1,NODE *head2);


main()
{
    NODE *a,*b,*c,*d;
    a=create_cir();
    b=create_cir();
    c=connect(a,b);
    d=c;
    printf("输入链接后的链表:");
    while(d->next!=c)
    {
        d=d->next;
        printf("%3d",d->data);
    }
}
   

NODE create_cir()
{
    NODE  *head,*p,*q;
    int a,n;
    head=(NODE *)malloc(sizeof(NODE));
    q=head;
    printf("输入链表的结点数:");
    scanf("%d",&n);
    q->data=n;
    if(n>0)
    {
        printf("输入链表:");
        while(n>0)
        {
            scanf("%d",&a);
            p=(NODE *)malloc(sizeof(NODE));
            p->data=a;
            q->next=p;
            q=p;
            n--;
        }
    }
    q->next=head;
    return(head);
}



NODE *connect(NODE *head1,NODE *head2)
{
        NODE *p,*q;
        p=head1->next;
        while(p->next!=head1)
            p=p->next;
        q=head2->next;
        while(q->next!=head2)
            q=q->next;
        p->next=head2->next;
        q->next=head1;
        free(head2);
        return (head1);
}

以上循环链表的程序有三个错误不知道怎样改

把三个错误报上来呀。

两个地方（声明和函数名）的NODE create_cir()
改为
NODE* create_cir()