删除链表第index个结点

#include <stdio.h>
#include <stdlib.h>
#include <iostream>
using namespace std;
struct student
{
    int  num;
    struct student* next;
};
//从键盘读入数据创建链表，新结点插入到尾部
struct student* createByTail()
{
    struct student* head;
    struct student* p1, * p2;
    int n;
    n = 0;
    p1 = p2 = (struct student*)malloc(sizeof(struct student));
    scanf("%d", &p1->num);
    head = NULL;  //首先置链表为空链表
    while (p1->num != -1)    //num为-1，意味着用户输入结束
    {
        n = n + 1;
        if (n == 1)            //创建第一个结点
            head = p1;
        else
            p2->next = p1;
        p2 = p1;            //p2始终指向最后一个结点（即尾指针）
        p1 = (struct student*)malloc(sizeof(struct student)); //p1指向新结点
        scanf("%d", &p1->num);
    }
    p2->next = NULL;  //切记：最后一个结点的next赋值为NULL
    return head;
}
//输出链表中的信息（num）
void  displayLink(struct student* head)
{
    struct student* p;
    p = head;
    printf("head-->");
    while (p != NULL)
    {
        printf("%d-->", p->num);
        p = p->next;
    }
    printf("tail\n");
}
//删除链表中第index个结点。index从1开始。
//由于可能删除第一个结点，所以函数返回头指针给主调函数
struct student* deleteNode(struct student* head, int index)
{
    if (!head) return head;
    struct student* p = head,*q;
    if (index == 1)//删除第一个结点
    {
        q = head;
        head = head->next;
        free(q);
        return head;
    }
    else//删除其他节点
    {
        int i = 1;
        while (p->next)
        {
            if (i == index - 1)
            {
                q = p->next;
                p->next = q->next;
                if(q)free(q);
                break;
            }
            i++;
            p = p->next;
        }
        return head;
    }
}
int main()
{
    struct student* head;
    int index;
    head = createByTail();
    while (scanf("%d", &index) != -1)
    {
        head = deleteNode(head, index);
        displayLink(head);
    }
}