分析下面的程序,下列说法中错误的是 ________ 。 #define NULL 0 #include "conio.h" struct stu { long num; char name[20]; int score; struct stu * next; }; int main() { struct stu *head,*p,*pa,*pb,*pc; pa=(struct stu *)malloc(sizeof(struct stu)); pb=(struct stu *)malloc(sizeof(struct stu)); pc=(struct stu *)malloc(sizeof(struct stu)); scanf("%ld%s%d",&pa->num,pa->name,&pa->score); scanf("%ld%s%d",&pb->num,pb->name,&pb->score); scanf("%ld%s%d",&pc->num,pc->name,&pc->score); head=pa; pa->next=pb; pb->next=pc; pc->next=NULL; p=head; while(p!=NULL) { printf("%ld,%s,%d\n",p->num,p->name,p->score); p=p->next; } }