//2 函数功能：计算每个学生各门课程的总分和平均分 
void AverSumofEveryStudent(STU stu[], int n, int m)
{
    int i, j;
    for (i=0; i<n; i++)
    {
        stu[i].sum = 0;
        for (j=0; j<m; j++)
        {
            stu[i].sum = stu[i].sum + stu[i].score[j];
        }
        stu[i].aver = m>0 ? stu[i].sum / m : -1;
        printf("student %d: sum = %.0f, aver = %.0f\n", 
i+1, stu[i].sum, stu[i].aver);
    }    
}