谭浩强的链表程序输入问题
如果链表程序的主函数中只调用creat函数,为什么在运行的时候输入第一个数据的时候会自动退出??#include <malloc.h>
#include <stdio.h>
#include <stdlib.h>
#define NULL 0
#define LEN sizeof(struct student)
//创建一个链表
struct student
{
long num;
float score;
struct student *next;
};
int n;
struct student *creat(void)
{
struct student *head;
struct student *p1,*p2;
n=0;
p1=p2=(struct student *)malloc(LEN);
scanf("%ld,%lf",&p1->num,&p1->score);
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);
}
void print(struct student *head)
{
struct student *p;
printf("\nNow,These %d records are:\n",n);
p=head;
if(head!=NULL)
do
{
printf("%ld %5.2f\n",p->num,p->score);
p=p->next;
}while(p!=NULL);
}
//删除节点的函数
struct student *del(struct student *head,long num)
{
struct student *p1,*p2;
if(head==NULL)
{
printf("\nlist null!\n");
goto end;
}
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;
free(p1);
}
else
printf("%ld not been found!\n",num);
end: return (head);
}
//对链表的插入操作
struct student *insert(struct student *head,struct student *stud)
{
struct student *p0,*p1,*p2;
p1=head;
p0=(struct student *)malloc(LEN);
memcpy(p0, stud, LEN);
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)
head=p0;
else
p2->next=p0;
p0->next=p1;
}
else
{
p1->next=p0;
p0->next=NULL;
}
}
n=n+1;
return(head);
}
void clear(struct student *head)
{
struct student *p = head;
while (p != NULL)
{
head = p->next;
free(p);
p = head;
}
}
main()
{
struct student *head;
printf("input records:\n");
head=creat();
print(head);
getch();
}