链表删除插入头结点打印出错
/*问题：输入数据后，删除头结点，并再插入数据后，打印输出后，会打印出原未被删除的头结点数据，这是哪里有问题啊？？？这是我看小甲鱼老师视频照着打的，小甲鱼老师是删除的第二个结点，所以没出现这个问题，这个问题是删除头结点才会出现的，
求大佬们帮帮看一下，是哪里有问题？代码校对无错*/
#include <stdio.h>
#include <malloc.h>
#include <stdlib.h>
#define LEN sizeof(struct student) //student结构的大小
struct student *creat(); //创建链表
struct student *del(struct student *head,int num); //del函数用于删除结点，*head即链表
//的头指针，num是要删除的结点num。
struct student *insert( struct student *head,struct student *stu_2); //第一个参数需要被插入的链表
//第二个参数待插入的结构的地址
void print(struct student *head); //打印链表
struct student
{
int num;
float score;
struct student *next;
};
int n; //全局变量，用来记录存放了多少数据。
void main()
{
struct student *stu,*p,stu_2;
int n;
stu = creat();
p = stu;
print( p );
printf("Please enter the num to delete: ");
scanf("%d",&n);
print( del(p,n) );
printf("\nPlease input the num to insert: ");
scanf("%d",&stu_2.num);
printf("Please input the score: ");
scanf("%f",&stu_2.score);
p = insert(stu,&stu_2);
print( p );
printf("\n\n");
system("pause");
}
struct student *creat()
{
struct student *head;
struct student *p1,*p2;
p1 = p2 = (struct student *)malloc(LEN); //LEn是student结构的大小
printf("Please enter the num :");
scanf("%d",&p1->num);
printf("Please enter the score :");
scanf("%f",&p1->score);
head = NULL;
n = 0;
while( p1->num )
{
n++;
if( 1 == n )
{
head = p1;
}
else
{
p2->next = p1;
}
p2 = p1;
p1 = (struct student *)malloc(LEN);
printf("\nPlease enter the num :");
scanf("%d",&p1->num);
printf("Please enter the score :");
scanf("%f",&p1->score);
}
p2->next = NULL;
return head;
}
void print(struct student *head)
{
struct student *p;
printf("\nThere are %d records!\n\n",n);
p = head;
if( head )
{
do
{
printf("学号为%d的成绩是%f\n\n",p->num,p->score);
p = p->next;
}while( p != NULL );
}
}
struct student *del( struct student *head,int num )
{
struct student *p1,*p2;
if( head == NULL ) //如果头结点指向NULL，这是一个空链表
{
printf("\nThis list is null!\n");
goto END;
}
p1 = head;
while( p1->num !=num && p1->next != NULL)
{
p2 = p1;
p1 = p1->next;
}
if( num == p1->num )
{
if( p1 == head ) //当将要删除的节点位于头结点的时候
{
head = p1->next;
}
else
{
p2->next = p1->next;
}
printf("Delete No: %d succeed!\n",num);
n = n-1; //n是作为一个全局变量，用来记录链表的数据。
}
else
{
printf("%d not been found!\n",num);
}
END:
return head;
}
struct student *insert( struct student *head,struct student *stu_2)
{
struct student *p0,*p1,*p2;
p1 = head;
p0 = stu_2;
if( head == NULL )
{
head = p0;
p0->next = NULL;
}
else
{
while( (p0->num > p1->num) && (p1->next != NULL) )
{
p2 = p1;
p1 = p1->next;
}
if( p0->num <= p1->num )
{
if( head == p1 ) //p1是头结点，插入头部
{
head = p0;
}
else //普通情况，插入中间
{
p2->next = p0;
}
p0->next = p1;
}
else //p0的num最大，插入到末尾
{
p1->next = p0;
p0->next = NULL;
}
}
n += 1; //由于插入了，所以增加了一位数据成员进入链表中。
return head;
} 本帖最后由 Lightup 于 2021-1-23 19:05 编辑
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