链表：关于删除结点的问题

创建链表然后输出都可以，但删除一个结点就不行，会显示是空链。
请问怎么解决

#include<stdio.h>
#include<stdlib.h>
#define LEN sizeof(struct Student)

struct Student
{
    long num;
    float score;
    struct Student *next;
};
int n;

int main()
{
    struct Student *creat(void);
    struct Student *del(struct Student *head, long num);
    struct Student *pt, *pt1;
    long num;
    pt = creat();
    do
    {
        printf("\nnum:%ld\nscore:%5.1f\n", pt->num, pt->score);
        pt = pt->next;
    } while (pt != NULL);
    printf("删除的编号：");
    scanf("%ld", &num);
    pt1 = del(pt, num);
    do
    {
        printf("\nnum:%ld\nscore:%5.1f\n", pt1->num, pt1->score);
        pt1 = pt1->next;
    } while (pt1 != NULL);
    return 0;
}

struct Student *creat(void)
{
    struct Student *head, *p1, *p2;
    p1 = p2 = (struct Student*)malloc(LEN);
    scanf("%ld,%f", &p1->num, &p1->score);
    n = 0;
    head = NULL;
    while (p1->num != 0)
    {
        n = n + 1;
        if (n == 1)
            head = p1;
        else
            p2->next = p1;
        p2 = p1;
        p1 = (struct Student*)malloc(LEN);
        scanf("%ld,%f", &p1->num, &p1->score);
    }
    p2->next = NULL;
    return head;
}

struct Student *del(struct Student *head, long num)
{
    struct Student *p1, *p2;
    if (head == NULL)
    {
        printf("\nlist null!\n");
        return head;
    }
    p1 = head;
    while (num != p1->num&&p1->next != NULL)
    {
        p2 = p1; 
        p1 = p1->next;
    }
    if (num == p1->num)
    {
        if (p1 == head)
            head = p1->next;
        else
            p2->next = p1->next;
        printf("delete:%d\n", num);
        n = n - 1;
    }
    else
        printf("%ld not been found!\n", num);
    return head;
}

pt在输出的时候已经走到链表末尾变成空了，删除的时候用它做参数所以显示空链，在输出之前再设一个变量存储头指针就行

主函数第20行改为：

pt1 = pt = creat();

主函数第28行改为：

pt1 = del(pt1, num);