#include<stdio.h>
#include<malloc.h>
#include<string.h>
struct student
{ char name[50];
  int num;
  int grades;
};
void main()

{

    int i=0,j,k,exchang;struct student exchange;
   

struct student *stu;

  stu=(struct student *)malloc(100*sizeof(struct student));
  

printf("请输入学生的姓名,当姓名输入NULL时程序结束,按回车进入下一步");

scanf("%s",stu[i].name);


for(;strcmp(stu[i].name,"NULL");scanf("%s",stu[i].name))
{

printf("请输入学生的学号");

scanf("%d",&stu[i].num);

printf("请输入学生的成绩");


scanf("%d",&stu[i].grades);

i++;
}
i--;
for(k=i;k>0;k--)

  for(j=i;j>i-k;j--)

  {if(stu[j].num>stu[j-1].num)

  {strcpy(exchange.name,stu[j].name);

   strcpy(stu[j].name,stu[j-1].name);

   strcpy(stu[j-1].name,exchange.name);
  
   exchang=stu[j-1].num;

   stu[j-1].num=stu[j].num;

   stu[j].num=exchang;

   exchang=stu[j-1].grades;

   stu[j-1].grades=stu[j].grades;

   stu[j].grades=exchang;
  }
  }
 
  for(j=0;j<=i;j++)
     

  printf("name=%s,num=%d,grades=%d\n",stu[j].name,stu[j].num,stu[j].grades);
  while(1);

}