#include<stdio.h>
void main()
{
     struct student     
     {
          char name[20];
          int num;
          float math;   
          float eng;   
          float cuit;     
          float sum;
     }stu[4];
     struct student temp;
     int i,j,k;
     for(i = 0;i<4;i++)   
     {
          printf("input %d name = ?",i);
          gets(stu[i].name);
          printf("input %d num,math,eng,cuit = ?",i);
          scanf("%d%f %f %f ",&stu[i].num,&stu[i].math,
               &stu[i].eng , &stu[i].cuit);
          getchar();  
          stu[i].sum = stu[i].math+stu[i].eng+stu[i].cuit;
     }
     for(i = 0;i<3;i++)   
     {
          k = i;
          for(j = i+1;j<4;j++)
               if(stu[i].sum>stu[j].sum)   k = j;
          if(k!=i)
          {
               temp = stu[i].sum;/*这里为什么不能加.sum */
               stu[i].sum=stu[k].sum;
               stu[k].sum = temp;
          }
     }
     for(i = 0;i<4;i++)
     {
          printf("%-10s%d%8.2f%8.2f%8.2f%8.2f \n",
               stu[i].name,stu[i].num,stu[i].math,
               stu[i].eng,stu[i].cuit,stu[i].sum);
     }
}
e:\作业\dierxueqi\10\4.cpp(32) : error C2679: binary '=' : no operator defined which takes a right-hand operand of type 'float' (or there is no acceptable conversion)
e:\作业\dierxueqi\10\4.cpp(34) : error C2679: binary '=' : no operator defined which takes a right-hand operand of type 'struct main::student' (or there is no acceptable conversion)
如果改为这个
 if(k!=i)
          {
               temp = stu[i];
               stu[i]=stu[k];
               stu[k]= temp;
          }
     }
运行结果是[local]1[/local]也不对