C#: Value not persisting in postback

using System;
using System.Collections;
using System.Configuration;
using System.Data;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Xml.Linq;

public partial class expt2 : System.Web.UI.Page
{
    double result ;
    protected void Page_Load(object sender, EventArgs e)
    {
        if (!Page.IsPostBack)
            result = 0.0;
 protected void Chkbxbd_CheckedChanged(object sender, EventArgs e)
    {
        if (Chkbxbd.Checked)
        {
            txtbxttl.Text = "" + 10000;
            result += double.Parse(txtbxttl.Text);

        }
        else
            result = result - 10000;


      }
    protected void Chkbxsfa_CheckedChanged(object sender, EventArgs e)
    {
        if (Chkbxsfa.Checked)
        {
            txtbxttl.Text = "" + 15000;
            result += double.Parse(txtbxttl.Text);

        }
        else
            result = result - 15000;


    }
 protected void btnttl_Click(object sender, EventArgs e)
  开发者_StackOverflow社区  {
        txtbxttl.Text = "" + result;

    }
}

In this code the individual value for checkbox is ok but when the total is made it becomes 0.

Please help me to fix it.

---

The "result" value is not persisted through postbacks. Either recalculate it always when you need the final result or store it in the viewstate.

---

result variable will not be preerved in numereous post backs because the nature of web application is state less so tore the result in a ViewState or Session variable as shown below.

    public partial class expt2 : System.Web.UI.Page
{
    double result ;
    protected void Page_Load(object sender, EventArgs e)
    {
        if (!Page.IsPostBack)
              Session["result"] = 0.0;
    }
 protected void Chkbxbd_CheckedChanged(object sender, EventArgs e)
    {
        if (Chkbxbd.Checked)
        {
            txtbxttl.Text = "" + 10000;

            result = double.Parse(Session["result"].ToString());
            result += double.Parse(txtbxttl.Text);

            Session["result"] = result;

        }
        else
        {
             result = double.Parse(Session["result"].ToString());
             result = result - 10000;
             Session["result"]= result;
        }



      }
    protected void Chkbxsfa_CheckedChanged(object sender, EventArgs e)
    {
        if (Chkbxsfa.Checked)
        {
            txtbxttl.Text = "" + 15000;
            result = double.Parse(Session["result"].ToString());
            result += double.Parse(txtbxttl.Text);
            Session["result"] = result;

        }
        else
        {
            result = double.Parse(Session["result"].ToString());
            result = result - 15000;
            Session["result"] = result;
        }



    }
 protected void btnttl_Click(object sender, EventArgs e)
    {
        txtbxttl.Text = "" + Session["result"].ToString();

    }
}