why object refference not set error comes on this code.

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C#

using System;
using System.Collections.Generic;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data.SqlClient;
public partial class user_apointmentTicketPrint : System.Web.UI.Page
{
    Class1 ob = new Class1();
    protected void Page_Load(object sender, EventArgs e)
    {
        ob.conn();
            string pno = Session["pno"].ToString();
        ob.fetch("select * from patient_reg where pname='" + pno + "'");
        lblpno.Text = ob.ds.Tables[0].Rows[0].ItemArray[0].ToString();
        lbldrname.Text = ob.ds.Tables[0].Rows[0].ItemArray[7].ToString();
        lbldept.Text = ob.ds.Tables[0].Rows[0].ItemArray[6].ToString();
        lblpname.Text = ob.ds.Tables[0].Rows[0].ItemArray[1].ToString();
        lblage.Text = ob.ds.Tables[0].Rows[0].ItemArray[4].ToString();
        lblplace.Text = ob.ds.Tables[0].Rows[0].ItemArray[10].ToString();
    }
}

Posted 17-Mar-14 21:56pm

sipun002

Updated 17-Mar-14 22:02pm

Tadit Dash (ତଡିତ୍ କୁମାର ଦାଶ)

v3

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Comments

Tom Marvolo Riddle 18-Mar-14 4:00am

In which line?

2 solutions

Solution 1

Refer the most popular answer by Sergey "Object Reference not set to Instance of an object", please see the code below.[^].

Moreover, before using any property like Session, check if that is null or not.

Posted 17-Mar-14 22:03pm

Tadit Dash (ତଡିତ୍ କୁମାର ଦାଶ)

Updated 17-Mar-14 22:04pm

v2

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Abhinav S · Accepted Answer · 2014-03-17T22:08:00

Check if one of the following are null -

C#

ob.fetch("select * from patient_reg where pname='" + pno + "'");
       lblpno.Text = ob.ds.Tables[0].Rows[0].ItemArray[0].ToString();
       lbldrname.Text = ob.ds.Tables[0].Rows[0].ItemArray[7].ToString();
       lbldept.Text = ob.ds.Tables[0].Rows[0].ItemArray[6].ToString();
       lblpname.Text = ob.ds.Tables[0].Rows[0].ItemArray[1].ToString();
       lblage.Text = ob.ds.Tables[0].Rows[0].ItemArray[4].ToString();
       lblplace.Text = ob.ds.Tables[0].Rows[0].ItemArray[10].ToString();

Since you are using ToString on all of them, null will throw errors.
Try using Convert.ToString() instead.