null reference exception

Question

1.00/5 (1 vote)

See more:

hi,
i am getting an error null reference exception(object reference is not instantiated) in my code. i am trying to get the data using querystring.my code looks like this:

C#

string strTravels=string.empty;

then on button click-

C#

response.redirect("booking.aspx?Travels=+ strTravels+");

on the redirected page ihave written:

C#

lblname.text=request.querystring["Travels"].Tostring();

the error is showing null reference exception.

if i will write :

C#

if(Request.querystring["Travels"]!=null)
{
 lblname.text=request.querystring["Travels"].tostring();
}

then also the error is not getting resolved.can anybody suggest me how to resolve this error?m new to asp.net.

Posted 26-Feb-13 4:27am

shakti das

Updated 26-Feb-13 4:35am

DinoRondelly

v2

Add a Solution

2 solutions

Solution 2

You did not show where the exception with the message "Object reference not set to an instance of an object" is thrown.

Not to worry. This is one of the very easiest cases to detect and fix. It simply means that some member/variable of some reference type is dereferenced by using and of its instance (non-static) members, which requires this member/variable to be non-null, but in fact it appears to be null. Simply execute it under debugger, it will stop the execution where the exception is thrown. Put a break point on that line, restart the application and come to this point again. Evaluate all references involved in next line and see which one is null while it needs to be not null. After you figure this out, fix the code: wither make sure the member/variable is properly initialized to a non-null reference, or check it for null and, in case of null, do something else.

Please see also: want to display next record on button click. but got an error in if condition of next record function "object reference not set to an instance of an object"[^].

Good luck,

—SA

Posted 26-Feb-13 8:47am

Sergey Alexandrovich Kryukov

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

OriginalGriff · Accepted Answer · 2013-02-26T04:38:00

Solution 1

Check lblname - if it is null, you will get the null reference error even if the query string value exists.

Posted 26-Feb-13 4:38am

OriginalGriff

Comments

shakti das 26-Feb-13 10:40am

then what i have to write lblname!=null;

OriginalGriff 26-Feb-13 11:35am

Sounds like a start, yes! :laugh:

OriginalGriff 26-Feb-13 11:36am

Alternatively, you could check why it is null - that would be my favourite...