求帮我看一下应该怎么修改这个c++程序

/*原代码错误太多，以下代码基本上是重写的，请仔细阅读代码。*/#include #include #include typedef struct student {int num;char name[20];double score; struct student *link;}*linklist;linklist creatlist(int n) {linklist llist,p,q;p = llist = (linklist)malloc(sizeof(struct student));p->num = 0;p->name[0] = '\0';for(int i = 0;i num);printf("第%d/%d学生的姓名 : ",i + 1,n);scanf("%s",q->name);printf("第%d/%d学生的成绩 : ",i + 1,n);scanf("%lf",&q->score);printf("\n");p->link = q;p = q;}p->link = NULL;return llist;}void seachlist(linklist llist) {int n; linklist p = llist->link;printf("学号 : ");scanf("%d",&n);while((p != NULL) && (p->num != n)) p = p->link;if(p == NULL) printf("无此学生！\n\n");else printf("学号 : %d, 姓名 : %s, 成绩 : %6.2lf\n\n",p->num,p->name,p->score);}void setnewscore(linklist llist) { int n; linklist p;printf("学号 : ");scanf("%d",&n);p = llist->link;while((p != NULL) && (p->num != n)) p = p->link;if(p == NULL) printf("无此学生！\n\n");else {printf("请输入新成绩 : ");scanf("%lf",&p->score);}}void deletelink(linklist llist) {int n; linklist p,q;printf("学号 : ");scanf("%d",&n);p = llist->link;while((p != NULL) && (p->num != n)) p = p->link;if(p == NULL) printf("无此学生！\n\n");else {q = p->link;p = q->link;free(q);}}void insertpostlink(linklist llist) { int n; linklist p,q;printf("学号 : ");scanf("%d",&n);p = llist;while((p->link != NULL) && (p->link->num != n)) p = p->link;if(p->link != NULL) printf("该学生已在表中！\n\n");else {while((p->link != NULL) && (p->link->num != n)) p = p->link;q = (linklist)malloc(sizeof(struct student));printf("姓名 : ");scanf("%s",q->name);printf("成绩 : ");scanf("%lf",&q->score);q->num = n;p->link = q;q->link = NULL;}}void print(linklist llist) {linklist p = llist->link;while(p != NULL) {printf("学号:%d, 姓名:%s, 分数:%6.2lf\n",p->num,p->name,p->score);p = p->link;}}void whole(linklist llist,int an) {print(llist);switch(an) {case 1:print(llist);seachlist(llist);break;case 2:print(llist);setnewscore(llist);break;case 3:print(llist);insertpostlink(llist);break;case 4:print(llist);deletelink(llist);}}void freeheap(linklist head) {linklist p,q;p = head;q = p->link;while(q != NULL) {p = q;q = p->link;free(p);}free(head);}int main() {int an = 0;linklist llist = creatlist(3);print(llist);do {//system("CLS");printf("1:查询 2:更改 3:插入 4:删除 5:退出\n");printf("请输入 : ");scanf("%d",&an);whole(llist,an);}while(an != 5);freeheap(llist);return 0;}