多关键字排序的程序设计

#include<iostream> 
#include<stdlib.h> 
#include<time.h> 
using namespace std;
#define NUMBER 21 

struct student {
int num; //学生考号  
    int rank; //学生排名     
int sum; //学生总成绩     
int yuwenscore; //学生语文成绩     
int shuxuescore; //学生数学成绩     
int englishscore; //学生英语成绩     
struct student *next; 
};

struct order {  
int score;  
int num; 
}a[NUMBER];//辅助数组 

struct student *creat(struct student *head,int n) 
// 函数返回的是与节点相同类型的指针 
{
  int j=0;     
  struct student *p1,*p2;     
  p1=p2=new student; // 申请新节点  
  long t;     
 // srand((int)time(&t)); //随机数产生器     
  p1->num=++j; 

  p1->yuwenscore=rand() % 40+ 61; //由随机数产生器随机产生学生成绩  
  p1->englishscore=rand() % 40+ 61;  
  p1->shuxuescore=rand() % 40+ 61; 
  p1->sum=p1->yuwenscore+p1->shuxuescore+p1->englishscore;     
  p1->next = NULL; // 将新节点的指针置为空     
  for(int i=1;i<=NUMBER;i++) {
      if (head==NULL) head=p1; //空表，接入表头         
  else p2->next=p1; // 非空表，接到表尾         
  p2 = p1;         
  p1=new student; //申请下一个新节点   
  p1->next=NULL;         
  if(i<=NUMBER-1){
        p1->num=++j;            
            p1->yuwenscore=rand() % 40+ 61;          
p1->englishscore=rand() % 40+ 61;          
p1->shuxuescore=rand() % 40+ 61;    
p1->sum=p1->yuwenscore+p1->shuxuescore+p1->englishscore;   
  } //输入节点的值  
  }
  return head; //返回链表的头指针
}

void c(struct student *head)//按考号输出所有学生成绩 
{
  cout<<"各个学生成绩："<<endl;     
  cout<<"             考号"<<"     总分"<<"     语文成绩"<<"      数学成绩"<<"      英语成绩"<<endl;  
  while(head!=NULL)  {   
  cout<<"                 "<<head->num<<"        "<<head->sum<<"        "<<head->yuwenscore<<"            "<<head->shuxuescore<<"            "<<head->englishscore<<endl;   
  head=head->next; 
  }