长内容自动分页的实现 (asp.net C#)

 
public class t3 : System.Web.UI.Page
        {  
                private string str;//字符
                private int strl;//字符总长度
                private int pagesize;//每页显示的字符数
                private void Page_Load(object sender, System.EventArgs e)
                {
                        // 在此处放置用户代码以初始化页面  
                        str="1234567891234567898522555";
                        pagesize=3;
                        strl=str.Length;
                        Response.Write(strl);
                        substr();
                }
         private void substr()
                {