本身没错 但是就是在运行的时候不行...谁能告诉我为什么?
我把这个程序都传上来 你们看下 是关于动态链表的建立,输出,删除,插入的
#include <malloc.h>
#define null 0
#define len sizeof(struct student)
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,%f",&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("\nthese %d records are:\n",n);
p=head;
if(head!=null)
do
{printf("%ld%5.1f\n",p->num,p->score);
p=p->next;
}while(p!=null);
}

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:%ld\n",num);
n=n-1;
}
else printf("%ld not beeb found!\n",num);
return(head);
end:return null;
}

struct student *insert(struct student *head,struct student *stu)
{struct student *p0,*p1,*p2;
p1=head;
p0=stu;
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);
}

main()
{struct student *head,*stu;
long del_num;
printf("input records:\n");
head=creat();
print(head);
printf("\ninput the deleted number:");
scanf("%ld",&del_num);
while(del_num!=0)
{head=del(head,del_num);
print(head);
printf("\ninput the deleted number:");
scanf("%ld",&del_num);
}
printf("\ninput the inserted record:");
stu=(struct student *)malloc(len);
scanf("%ld,%f",&stu->num,&stu->score);
while(stu->num!=0)
{head=insert(head,stu);
print(head);
printf("\ninput the record:");
stu=(struct student *)malloc(len);
scanf("%ld,%f",&stu->num,&stu->score);
}
}

一下 引一位恢复者的话 :
void print(struct student *head)
{struct student *p;
printf("\nthese %d records are:\n",n);
p=head; /*p=head->next;*/
if(head!=null) /*if(p!=NULL) head 里面没有装数据不能输出数据*/
do
{printf("%ld%5.1f\n",p->num,p->score);
p=p->next;
}while(p!=null);
}

void main()
{
..
print(head);
..
}
也就是说 head变量被用了多次　没个调用函数都用了不同的ｈｅａｄ　
请问还有别的意见不？

估计是建链表的问题.参考一下.
#include<stdio.h>
#include<malloc.h>

typedef struct List_Node{
int info;
struct List_Node *next;
}node;//结点结构体
/******************************/
/* 尾插法建立带头结点的单链表 */
/******************************/
node* Creat_Node()
{
node *head,*pre,*p;
int x;
head=(node*)malloc(sizeof(node));;
head->next=NULL;
pre=head;
printf("输入各结点的值,以0结束:");
while(EOF!=(scanf("%d",&x))&&x!=0)
{
p=(node*)malloc(sizeof(node));
p->info=x;
p->next=pre->next;
pre->next=p;
pre=pre->next;
}
return head;
}

/******************************/
/* 头插法建立带头结点的单链表 */
/******************************/
node* Build_Node()
{
node *head,*p;
int x;
head=(node*)malloc(sizeof(node));;
head->next=NULL;
printf("输入各结点的值,以0结束:");
while(EOF!=(scanf("%d",&x))&&x!=0)
{
p=(node*)malloc(sizeof(node));
p->info=x;
p->next=head->next;
head->next=p;
}
return head;
}

/******************************/
/* 打印单链表 */
/******************************/

void Print_Node(node *head)
{
node *p=head->next;
printf("输出该链表:");
while(p)
{
printf("%-5d--->",p->info);
p=p->next;
}
if(p==NULL)
{
printf("^\n\n\n");
}
}