c#里对象的一个问题

[cy527300280]

public partial class 基础_obj_this : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        book b1=new book("ASP.NET",24.4f);
        book b2 = new book("XML", 22f);
        book[] arr = new book[] { b1,b2 };
        //sinfo s = new sinfo("张三", "男", 20, arr);
        sinfo s2 = new sinfo("张三", "男", 20, arr);
        Response.Write(s2.info());
    }
}
class sinfo
{
    private string name;
    private string sex;
    private uint age;
    private book[] b;
    public sinfo(string n, string s, uint a, book[] b)
    {
        this.age = a;
        this.sex = s;
        this.name = n;
        this.b=b;
    }
    public string info()
    {
        string all = "";
        foreach (book t in b) 
        {
            all += t.bookinfo;
            
        }
       
        return "姓名：" + this.name + "<br>性别：" + this.sex + "<br>年龄：" + this.age + "<br>书籍信息:" + all;
    }
}
class book
{
    private string bookn;
    private float price;
    public book(string bn,float p)
    {
        this.bookn = bn;
        this.price = p;
    }
    public string bookinfo()
    {
        return this.bookn+","+this.price;
    }
}

请问下：
1、 foreach (book t in b)
{
all += t.bookinfo;

}
这个t.bookinfo是什么啊，我知道b是传过来的arr数组，t是book类型的，如果直接用 all+=t，结果输出来是 book book
2、这个book是类，怎么实例化后加个[]就成了数组了

[zgke]

all是事件...事件是可以委托

当第1次执行all+=t.bookinfo; 的时候

all[0] ==> b[0].bookinfo;
all[1] ==> b[1].bookinfo;

all里有两个方法..当all被除法的时候 会全部调用.