[求助]删除结点的问题

#include<malloc.h>
#define NULL 0
#define LEN sizeof(struct student)
struct student
{long num;
float score;
struct student *next;
};
int n;
struct student *cread(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;
reture(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 %5.1f\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 been found!\n",num);
return(head);
}

struct student * insert(struct student *head,struct student *stud)
{struct student *p0,*p1,*p2;
p1=head;
p0=stud;
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;}
{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("input 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("input the inserted redord:");
stu=(struct student * )malloc(LEN);
scanf("%ld,%f",&stu->num,&stu->score);
}
getch();
}

这个我是按书上写的，好像删除结点的部分不对，我不知道错在哪里？
望各位大侠帮我看看！先谢谢啦

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再仔细看看书吧，呵呵

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