链表循环插入数据遇到问题，请神帮助！
程序代码：#include<stdio.h>
#include<stdlib.h>
#define LEN sizeof(struct student)
struct student *creat();
struct student *del(struct student *head,int num);
int print(struct student *head);
//******************************************//
int n;
//******************************************//
struct student
{
int num;
float score;
struct student *next;
};
struct student *creat()
{
struct student *head,*p1,*p2;
p1=p2=(struct student*) malloc(LEN);
printf("input the num: ");
scanf("%d",&p1->num);
printf("input the score: ");
scanf("%f",&p1->score);
head=NULL;
n=0;
while(p1->num!=0)
{
n++;
if(n==1)
{
head=p1;
}
else
{
p2->next=p1;
}
p2=p1;
p1=(struct student*) malloc(LEN);
printf("input the num:");
scanf("%d",&p1->num);
printf("input the score: ");
scanf("%f",&p1->score);
}
p2->next=NULL;
return (head);
}
int print(struct student *head)
{
struct student *p;
p=head;
printf("There are %d records:\n",n);
printf("\t\tnum\t\tscore\n");
while(p!=NULL)
{
printf("\t\t%d\t\t%f\n",p->num,p->score);
p=p->next;
}
}
struct student *del(struct student *head,int y)
{
struct student *p1,*p2;
if(head==NULL)
{
printf("This list is null\n");
return (NULL);
}
p1=head;
while( (p1->num != y )&& (p1->next != NULL))
{
p2 = p1;
p1 = p1->next;
}
if( y == p1->num )
{
if( p1 == head )
{
head = p1->next;
}
else
{
p2->next = p1->next;
}
printf("\nDelete No: %d succeed!\n", y);
n = n-1;
}
else
{
printf("%d not been found!\n", y);
}
return (head);
}
struct student *add(struct student*head,struct student *stu1)
{
struct student *p1,*p0,*p2;
p1=head;
p0=stu1;
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(p1==head)
{
head=p0;
p0->next=p1;
free(p1);
p1=p0->next;
}
else
{
p2->next=p0;
p0->next=p1;
free(p1);
p1=p0->next;
}
}
else
{
p1->next=p0;
p0->next=NULL;
}
n=n+1;
}
return(head);
}
void main()
{
struct student *q,*stu,stu2;
int x;
int a;
stu=creat();
q=stu;
print(q);
printf("How do you want to do:del='1',add='2'\n");
scanf("%d",&a);
if(a==1)
{
do
{
printf("please input the num of you want to deleat: ");
scanf("%d",&x);
q=del(q,x);
if(q==NULL)
{
break;
}
print(q);
}while(x!=0);
}
else
{
do
{
printf("\nplease input the num you want to insert: ");
scanf("%d",&stu2.num);
printf("please input the score you want to insert: ");
scanf("%f",&stu2.score);
q=add(q,&stu2);
if(q==NULL)
{
break;
}
print(q);
}while(stu2.num!=0);
}
printf("\n\n");
system("pause");
}
以上是源代码，有循环输出、删除、添加一个结构体（学生成绩和学号）的功能，但是对于
循环插入功能：
struct student *add(struct student*head,struct student *stu1)
{
struct student *p1,*p0,*p2;
p1=head;
p0=stu1;
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(p1==head)
{
head=p0;
p0->next=p1;
free(p1);
p1=p0->next;
}
else
{
p2->next=p0;
p0->next=p1;
free(p1);
p1=p0->next;
}
}
else
{
p1->next=p0;
p0->next=NULL;
}
n=n+1;
}
return(head);
}
void main()
{
struct student *q,*stu,stu2;
int x;
int a;
stu=creat();
q=stu;
print(q);
printf("How do you want to do:del='1',add='2'\n");
scanf("%d",&a);
if(a==1)
{
do
{
printf("please input the num of you want to deleat: ");
scanf("%d",&x);
q=del(q,x);
if(q==NULL)
{
break;
}
print(q);
}while(x!=0);
}
else
{
do
{
printf("\nplease input the num you want to insert: ");
scanf("%d",&stu2.num);
printf("please input the score you want to insert: ");
scanf("%f",&stu2.score);
q=add(q,&stu2);
if(q==NULL)
{
break;
}
print(q);
}while(stu2.num!=0);
}
printf("\n\n");
system("pause");
}
运行后结果会无限循环，并不是得到想要的功能。这是为什么？在线等！
