程序代码：

#include "stdio.h"
#include "string.h"
#include "stdlib.h"
#define N 5
struct score               
{
  char name[10]; 
  float math,eng;     
};

void sort(double a[N],struct score s[N])     //排序，用平均值排序，返回结构体变量
{ int i,k,m;struct score t1;double t2;
  for(i=1;i<N;i++)
  { m=i-1;
    for(k=i;k<N;k++)
      if(a[m]>a[k]) m=k;
    if(m!=i-1) 
     {
       t1=s[i-1];s[i-1]=s[m];s[m]=t1;     
       t2=a[i-1];a[i-1]=a[m];a[m]=t2;
     } 
  }
}


main()                                        //主函数
{ struct score s[N]; int i; double avg[N];
  for(i=0;i<N;i++)
   {
       printf("name:");
       fflush(stdin);
       gets(s[i].name);
       printf("maths english:");
       scanf("%f%f",&s[i].math,&s[i].eng);
   }
  
  for(i=0;i<N;i++)
   avg[i]=(s[i].math+s[i].eng)/2;
  
  sort(avg,s);
  
  for(i=0;i<N;i++)
   printf("%s\t%.1f\t%.1f\n",s[i].name,s[i].math,s[i].eng);
   
}