有序链表合并，，为什么输出不了？？

#include<stdio.h>
#include<malloc.h>
typedef struct lianbiao *List;
struct lianbiao{//格式 
    int data;
    List next;
};
List create(List L);
void link(List L1,List L2);
int main(){
    List L1,L2;
    L1=create(L1);
    L2=create(L2);
    
    link(L1,L2);
    
    return 0;
}
List create(List L){
    L=NULL;
    List tail=NULL,p;
    while(1){
        p=(List)malloc(sizeof(struct lianbiao));
        p->next =NULL;
        scanf("%d",&p->data );
        if(p->data ==-1)break;
        if(L==NULL)L=p;
        else
            tail->next =p;
        tail=p;
    }
    return L;
}
void link(List L1,List L2){
    List p1=L1,p2=L2,tail=NULL,head=NULL,p;
    if(L1==NULL&&L2==NULL){
        printf("NULL");
        return;
    }
    while(1){
        if(p1->data >p2->data ){
            p=(List)malloc(sizeof(struct lianbiao));
            p->next =NULL;
            p->data =p2->data ;
            p2=p2->next ;
        }
        else{ 
            p=(List)malloc(sizeof(struct lianbiao));
            p->next =NULL;
            p->data =p1->data ;
            p1=p1->next ;
        }
        
        if(head==NULL)head=p;
        else tail->next =p;
        tail=p;
    if(p1==NULL&&p2==NULL)break;
}
    
    p=head;
    while(p!=NULL){
        printf("%d",p->data );
        p=p->next ;
    }

}

新建一个链表为合并链表，but这个要怎么解决？？

因为你最后的while没有括号，只有data在里面，next不在里面，所以p永远不为null，永远打印，死循环了，直到输出缓冲区溢出报错

修改如下，供参考：

#include<stdio.h>
#include<malloc.h>
typedef struct lianbiao* List;
struct lianbiao {//格式 
    int data;
    List next;
};
List create(List L);
void link(List L1, List L2);
int main() {
    List L1, L2;
    L1 = create(L1);
    L2 = create(L2);

    link(L1, L2);

    return 0;
}
List create(List L) {
    L = NULL;
    List tail = NULL, p;
    while (1) {
        p = (List)malloc(sizeof(struct lianbiao));
        p->next = NULL;
        scanf("%d", &p->data);
        if (p->data == -1) {
            free(p);        //修改
            break;
        }
        if (L == NULL)
            L = p;
        else
            tail->next = p;
        tail = p;
    }
    return L;
}
void link(List L1, List L2) {
    List p1 = L1, p2 = L2, tail = NULL, head = NULL, p;
    if (L1 == NULL || L2 == NULL) {
        printf("NULL");
        return;
    }
    while (1) {
        if (p1->data > p2->data) {
            //p = (List)malloc(sizeof(struct lianbiao));
            //p->next = NULL;
            //p->data = p2->data;
            p = p2;
            p2 = p2->next;
        }
        else {
            //p = (List)malloc(sizeof(struct lianbiao));
            //p->next = NULL;
            //p->data = p1->data;
            p = p1;
            p1 = p1->next;
        }
        if (head == NULL)
            head = p;
        else 
            tail->next = p;
        tail = p;
        if (p1 == NULL || p2 == NULL) break;  //if (p1 == NULL && p2 == NULL)break;
    }
    tail->next = p1 ? p1 : p2;
    p = head;
    while (p != NULL) {
        printf("%5d", p->data);
        p = p->next;
    }
}