编译出错，大家帮忙看看啊。

1>d:\竹林晚风\documents\visual studio 2008\projects\qqq\qqq\qqq.cpp(54) : error C2109: 下标要求数组或指针类型
1>d:\竹林晚风\documents\visual studio 2008\projects\qqq\qqq\qqq.cpp(54) : error C2228: “.output”的左边必须有类/结构/联合


// qqq.cpp : 定义控制台应用程序的入口点。
//

#include "stdafx.h"
#include<iostream>
using namespace std;
class Book
{
private:
    char name[100];
    char num[20];
    char abstracts[100];
public:
    void input()
    {
        cout<<"Please input the name of the book:"<<endl;
        cin>>name;
        cout<<"Please input the num of the book:"<<endl;
        cin>>num;
        cout<<"Please input the abstract of the book:"<<endl;
        cin>>abstracts;
    }
    void output()
    {
        cout<<"The name of the book is :"<<name<<endl;
        cout<<"The num of the book is :"<<num<<endl;
        cout<<"The abstract of the book is :"<<abstracts<<endl;
    }
};
class Student
{
private:
    char name[100];
    char ID[50];
    Book a[5];
public:
    void inputs()
    {
        cout<<"Please input the name of the student :"<<endl;
        cin>>name;
        cout<<"Please input the ID of the student :"<<endl;
        cin>>ID;
    }
    void inputb(int i)
    {
        a[i].input();
    }
    void outputs (int a)
    {
        cout<<"The name of the student is :"<<name<<endl;
        cout<<"The ID of the student is:"<<ID<<endl;
        for (int j=0;j<a;j++)
        {
            a[j].output();
        }
    }
};



int _tmain(int argc, _TCHAR* argv[])
{
    Student stu;
    stu.inputs ();
    cout<<"Do you want to borrow a book?"<<endl;
    char s;
    cin>>s;
    int k=0;
    while (s=='Y'||s=='y')
    {
        
        stu.inputb(k);
        k++;
        if(k==5)
        {
            cout<<"you can't borrow a book more!"<<endl;
            break;
        }
    }
    cout<<"The massage you inputed are:"<<endl;
    stu.outputs (k);


    return 0;
}