Object reference not set to an instanc of an object

Question

3.00/5 (1 vote)

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When I try to open the page from IDE using VIEW IN BROWSER option, I get
"Object reference not set to an instance of an object" error.
The code I get this error is as follows:

C#

XResult = Request.QueryString["res"];
TextBox1.Text = XResult.ToString();

Thanks.

Posted 4-Mar-11 8:30am

maadhukari

Updated 4-Mar-11 8:43am

TweakBird

v3

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#realJSOP · Accepted Answer · 2011-03-04T08:46:00

Solution 2

Either the Request object is null, or XResult is null, meaning the querystring element "res" does not exist in the querystring.

Posted 4-Mar-11 8:46am

#realJSOP

Updated 4-Mar-11 8:48am

v2

OriginalGriff · Accepted Answer · 2011-03-04T08:46:00

Solution 3

Only two possibilities: either XResult or TextBox1 is null.

The later is unlikely - you should know if it is.

The most likely is that the XResult is null, implying that the Request.QueryString is returning null. The most likely reason for this is simple: Have you checked that there is a input on your form with the name "res"?

Posted 4-Mar-11 8:46am

OriginalGriff

Comments

Sergey Alexandrovich Kryukov 4-Mar-11 15:35pm

Almost 100% certain, my 5.
--SA

TweakBird · Accepted Answer · 2011-03-04T08:49:00

Assume,

if Request.QueryString["res"] it is Null, What happens in second line.

Your are trying to Conversion of null to string. That is reason for getting 'Object reference not set to an instance of an object' error.

So, What you have to do is,

Check if Query string is not null then do conversion. like this

C#

if(Request.QueryString["res"]!=null)
{
XResult = Request.QueryString["res"];
TextBox1.Text = XResult.ToString();
}
else
{
//---- Handle with out query string

}

wizardzz · Accepted Answer · 2011-03-04T08:45:00

Solution 1

Perhaps res is not being set to anything in the request (URL with a '?'), so your XResult is never set to anything?

Posted 4-Mar-11 8:45am

wizardzz

Comments

wizardzz 4-Mar-11 16:20pm

Why the heck did I get a 3? I posted this answer first, and other answers that provided the same logic got a 5, and came after mine.

#realJSOP 5-Mar-11 13:24pm

Sometimes that happens. I think all of us answered at about the same time, and when that happens, the highest rated user's answer is listed first, so it's the one the user sees first. It's happened to me when Nish and I answer at the same time - his response is listed before mine. Once voting starts to happen, though, the order changes to the highest rated until the OP marks one as answered, and then the other sorting starts kicking in again. I don't know why yours was 3-voted.