谁帮我看下这个程序，很简单，就想求3个学生成绩的总分及平均分，但输入2，结果是正确的，输入3为什么不行啊？

#include <iostream>
using namespace std;

class Student
{
public:
Student(int n,int a,float s): num(n),age(a),score(s){}
float total();
float average();

private:
int num,age,score;
static float sum;
static int count;
};

float Student::total()
{
sum=sum+score;
count++;
return sum;
}

float Student::average()
{
return (sum/count);
}

float Student::sum=0;
int Student::count=0;

int main()
{
Student stu[3]=
{
Student(1001,21,11),
Student(1002,22,12),
Student(1005,28,13),
};

int n;
cout<<"please enter the number of the student: ";
cin>>n;
for(int i=0;i<n;i++)
stu[i].total();
cout<<"the sum of the student's score is: "<<stu[i].total()<<endl;
cout<<"the average score of "<<n<<" students is "<<stu[i].average()<<endl;
return 0;
}

为什么输入2，答案才是正确的，输入3，反而错了。。。

以下是引用lusamy在2006-11-18 14:49:07的发言：

cin>>n;
for(int i=0;i<n;i++)
stu[i].total();
cout<<"the sum of the student's score is: "<<stu[i].total()<<endl;
cout<<"the average score of "<<n<<" students is "<<stu[i].average()<<endl;

当你输入3时，for循环已经统计完了3个学生的成绩。
退出循环时，i值为3，你调用stu[3].total结果就是未定义了。
因此，你的程序只要输入2，就能完成3个学生的计算了

[此贴子已经被作者于2006-11-18 15:10:50编辑过]

恩，想出来了，应该是这两句：
cout<<"the sum of the student's score is: "<<stu[i].total()<<endl;
cout<<"the average score of "<<n<<" students is "<<stu[i].average()<<endl;
出现了重复调用对象stu[i]，但是应该怎么修改才能正确显示呢？

[QUOTE]for(int i=0;i<n;i++)
stu[i].total();
cout<<"the sum of the student's score is: "<<stu[i].total()<<endl;
cout<<"the average score of "<<n<<" students is "<<stu[i].average()<<endl;
[/QUOTE]
for(int i=0;i<n;i++)
stu[i].total();//这里调用了一次stu.total（）；
cout<<"the sum of the student's score is: "<<stu[i].total()<<endl;//这里又调用了一次stu[i].total()等于就是重复调用了函数sum=sum+score;
改为：
for(int i=0;i<n;i++)

{ cout<<"the sum of the student's score is: "<<stu[i].total()<<endl;

cout<<"the average score of "<<i<<" students is "<<stu[i].average()<<endl;
cout<<"---------------------------------------"<<endl;
}