Null reference error in visual studio 2008

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Line 17:     {
Line 18:         //checks if user is login or not
Line 19:         if (Session["islogin"].ToString() == "false")
Line 20:         {
Line 21:             Response.Redirect("LoginPage.aspx");

Source File: c:\Users\INTIME\Desktop\New folder\Web Application Project\Project-Online Travel Agency\Billing.aspx.cs    Line: 19 

Stack Trace: 


[NullReferenceException: Object reference not set to an instance of an object.]
   OfflinePayment.Page_Load(Object sender, EventArgs e) in c:\Users\INTIME\Desktop\New folder\Web Application Project\Project-Online Travel Agency\Billing.aspx.cs:19
   System.Web.Util.CalliHelper.EventArgFunctionCaller(IntPtr fp, Object o, Object t, EventArgs e) +14
   System.Web.Util.CalliEventHandlerDelegateProxy.Callback(Object sender, EventArgs e) +35
   System.Web.UI.Control.OnLoad(EventArgs e) +99
   System.Web.UI.Control.LoadRecursive() +50
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +627

in the code

C#

public partial class OfflinePayment : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        //checks if user is login or not
        if (Session["islogin"].ToString() == "false") //LINE-19
        {
            Response.Redirect("LoginPage.aspx");
        }
        LblDateError.Visible = false;
        Lblservice.Text = Session["service"].ToString().ToUpper();
        Lblservice1.Text = Session["service"].ToString();
        Lblserviceid.Text = Session["serviceId"].ToString();
        Lbldate.Text = DateTime.Now.ToString();
        LblCostPerson.Text = Session["cost_per_person"].ToString();
        Lblcust.Text = Session["custId"].ToString();
    }

please help me solve this problem.

Posted 3-Dec-12 19:00pm

nitsgoyal

Updated 3-Dec-12 19:18pm

Wendelius

v2

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Comments

Programm3r 4-Dec-12 1:06am

Hi - Well it would seem that you have a NullReferenceException at line #19. So put a breakpoint at line #19 and check which variable is null.

My guess is, that one of the Session indexes doesn't exist, and by calling ToString() on it causes the NullReferenceException

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Mohd. Mukhtar · Answer 1 · 2012-12-03T19:14:00

Hi,

Update your code as below.

C#

public partial class OfflinePayment : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        //checks if user is login or not
        if(Session["islogin"] == null ||  Session["islogin"].ToString() == "false")
             Response.Redirect("LoginPage.aspx");

        LblDateError.Visible = false;
        Lblservice.Text = Session["service"].ToString().ToUpper();
        Lblservice1.Text = Session["service"].ToString();
        Lblserviceid.Text = Session["serviceId"].ToString();
        Lbldate.Text = DateTime.Now.ToString();
        LblCostPerson.Text = Session["cost_per_person"].ToString();
        Lblcust.Text = Session["custId"].ToString();
}

This may help you.

Aarti Meswania · Answer 2 · 2012-12-03T19:21:00

problem is,
Session["islogin"].ToString()

your session named "isLogin" is not created so gives null value,
so,
Session["islogin"] = Null
and in this case run time statement is,
Null.ToString()

and Null are not coverted in string (they haven't this method you are accessing)

so, please make sure that "islogin" session is created and after that you can use it,

else put condition,

C#

if (session["islogin"] != Null)
{
   if (Session["islogin"].ToString() == "false") 
   {
     ....
   }
}

Happy Coding!
:)

Null reference error in visual studio 2008

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