Re: NullReferenceException untraceable - C# Discussion Boards

20-Sep-09 10:10

Hi,

I am using unmanaged Dll in a managed C# project, where callbacks are made from the unmanaged code to the managed code.

My project compiles fine, when I run the application (in debug mode), which is basically a client that communicates with a server application, intermittently I get a NullReferenceException dialog box. But my problem is it does not point to a specific line of code where this exception is occurring. The dialog just shows in the middle of the IDE (VS 2008) and I have to stop the application.

Does anyone know how can I verify where this exception is occurring???

Appreciate your suggestions.

Re: NullReferenceException untraceable [modified]

Abhishek Sur20-Sep-09 10:31

Abhishek Sur

20-Sep-09 10:31

This happens sometimes when error is happening to an external dll. Say you have added a dll called a.dll which doesnt have the pdb associated with it or no Debug Symbols for that dll is loaded into memory... Thus .NET cant show you the actual source, and hence shows this error.

You can see the assembly code.. but if you dont know it, it wouldnt be meaningful to you.

What you can do is always add the dll from bin folder of your project. This ensures that the dll is loaded with debug symbols.

Smile | :)

Abhishek Sur

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akhanal20-Sep-09 10:37

20-Sep-09 10:37

I have added the dll from bin folder of the project.

modified on Sunday, September 20, 2009 4:43 PM

akhanal20-Sep-09 10:44

20-Sep-09 10:44

I mean I have been doing that already before I posted this question, It did not help.

Luc Pattyn20-Sep-09 11:03

Luc Pattyn

20-Sep-09 11:03

try copying both the DLL and the PDB file to the EXE folder.
that may suffice to get line numbers in your exception.

Smile | :)

Luc Pattyn

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akhanal21-Sep-09 4:07

21-Sep-09 4:07

Both of them are in the "bin\x64\Debug\" along with the EXE.

Abhishek Sur20-Sep-09 11:04

Abhishek Sur

20-Sep-09 11:04

What exactly the operation you are doing when you encounter this exception..??

the line no is not shown only when the source is not associated with debug information..
Debug line by line to find exact line where error is occurring..

Also see if there is anything in InnerException (Though I think it should be null)

Abhishek Sur

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proxy page rank

Omar Gameel Salem20-Sep-09 9:57

Omar Gameel Salem

20-Sep-09 9:57

is there such a thing?

re: proxy page rank

Pete O'Hanlon20-Sep-09 11:02

Pete O'Hanlon

20-Sep-09 11:02

nicromonicon wrote:
is there such a thing?

And this relates to C# how?

"WPF has many lovers. It's a veritable porn star!" - Josh Smith

As Braveheart once said, "You can take our freedom but you'll never take our Hobnobs!" - Martin Hughes.

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Omar Gameel Salem20-Sep-09 11:05

Omar Gameel Salem

20-Sep-09 11:05

actually i didnt know where to post it, its network related but i couldnt find network category

Pete O'Hanlon20-Sep-09 11:42

Pete O'Hanlon

20-Sep-09 11:42

So why on earth did you pick C#? It looks like you just picked a random forum, which isn't going to get you an answer. You might as well have asked this in Pig Farmers Weekly. You could have chosen the General IT Issues or, more appropriately, the Hardware and Devices forum.

"WPF has many lovers. It's a veritable porn star!" - Josh Smith

As Braveheart once said, "You can take our freedom but you'll never take our Hobnobs!" - Martin Hughes.

My blog | My articles | MoXAML PowerToys | Onyx

Omar Gameel Salem20-Sep-09 11:58

Omar Gameel Salem

20-Sep-09 11:58

i did it because i wanted to know - also - how to connect to a proxy via C#

anyway-Mr.O'Hanlon-dont you think by the time it took you to write down those not-so-funny rants and cheap jokes, you could've answered my question instead?

a true professional would have answered my question, or at least guide me to the correct forum

so next time, if you do know the answer,by all means, if you dont, please refrain from making useless comments..other members are not here for the jokes

Pete O'Hanlon20-Sep-09 12:29

Pete O'Hanlon

20-Sep-09 12:29

nicromonicon wrote:
i did it because i wanted to know - also - how to connect to a proxy via C#

Then you should have stated that, and not asked an unrelated question. We can't read your mind for you.

nicromonicon wrote:
anyway-Mr.O'Hanlon-dont you think by the time it took you to write down those not-so-funny rants and cheap jokes, you could've answered my question instead?

No I don't. This isn't the right forum for this - think about it for a minute. People search these forums for answers to questions; why do you think that somebody would look for a network question in the C# forum? It makes no sense.

nicromonicon wrote:
a true professional would have answered my question, or at least guide me to the correct forum

And had you read my reply you'd see that I suggested two possible forums for you.

Anyway, I'm not going to bother reading your replies now - whenever somebody replies in the way you just have, it's apparent they are incapable of a rational dialogue.

"WPF has many lovers. It's a veritable porn star!" - Josh Smith

As Braveheart once said, "You can take our freedom but you'll never take our Hobnobs!" - Martin Hughes.

My blog | My articles | MoXAML PowerToys | Onyx

help with both grouping plz

Richard MacCutchan20-Sep-09 21:49

Richard MacCutchan

20-Sep-09 21:49

nicromonicon wrote:
other members are not here for the jokes

Oh yes we are Laugh | :laugh:

rename [Main Report] tab

Jassim Rahma20-Sep-09 8:13

Jassim Rahma

20-Sep-09 8:13

In Crystal report viewer, is there any way to rename the tab [Main Report] showing at the top of the report to any name which I will decide?

Jassim Rahma20-Sep-09 8:11

Jassim Rahma

20-Sep-09 8:11

i have the following field:

trxn_date
trxn_category
trxn_description
trxn_total_amount
trxn_discount_amount
trxn_net_amount

I want to display a monthly report (all above excep trxn_category) based of the selected month so it will list by days from 1 to last day of the month.

at the bottom, I want to display the list by category for the whole month (without trxn_date and trxn_description) so it will be:

trxn_category
trxn_description
trxn_total_amount
trxn_discount_amount
trxn_net_amount

can you please guide...

Re: help with both grouping plz

Abhishek Sur20-Sep-09 10:58

Abhishek Sur

20-Sep-09 10:58

Let me know what reporting engine you are using... Is it Crystal Report, Microsoft Reporting (RDLC) or any other??

In any case just make grouping to those elements and place the group elements in the group footer. Use appropriate functions, and I think it will adjust automatically. Smile | :)

Abhishek Sur

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Create CLR objects in SQL Server 2005
C# Uncommon Keywords
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Problem Reading And Writing Registry In C#

Ben Magee20-Sep-09 5:06

Ben Magee

20-Sep-09 5:06

Hi guys,

I have this code in my form1_load event:

 RegistryKey licenseCheck = Registry.LocalMachine.OpenSubKey(@"software/openorganise");
 string licenseCo = licenseCheck.GetValue("tlb").ToString();
DateTime licenseDate = Convert.ToDateTime(licenseCo);
     if (licenseDate.AddDays(30) == System.DateTime.Now)
     {
         MessageBox.Show("Your OpenOrganise License Has Expired. Please Purchase A New One.", "OpenOrganise Message.", MessageBoxButtons.OK, MessageBoxIcon.Warning);
         Application.Exit();
     }

now, ive got a config value that sets it to write to a file if its the first time run or not, etc etc, this works fine, in the event of a first run i have:

RegistryKey licenseKey;
                licenseKey = Registry.LocalMachine.CreateSubKey(@"Software\openorganise");
                licenseKey.SetValue("tlb",DateTime.Now);
                Registry.LocalMachine.Flush();

However, when running the application i get: "object referance not set to a instance of a object"

Im stumped to as why. I even went and manually made the reg key.

thanks,
Ben.

Luc Pattyn20-Sep-09 5:21

Luc Pattyn

20-Sep-09 5:21

Hi,

some remarks:

1.
exceptions tend to contain a lot of information, however you need to look at all of it, i.e. use Exception.ToString() instead of Exception.Message

one of the pieces of information it offers is a filename and linenumber; that would point straight to the culprit line. Also teach your IDE to always show line numbers in edit windows, see here[^].

2.
Recent Windows versions don't allow a regular user to access/modify system settings that would extend to other users; the LocalMachine registry hive would be in that category.

3.
Your expiration test needs a less than comparison, not an equals. DateTimes seldom are equal as they contain information up to the tick (one tenth of a microsecond).

Smile | :)

Luc Pattyn

Have a look at my entry for the lean-and-mean competition; please provide comments, feedback, discussion, and don’t forget to vote for it! Thank you.

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Richard MacCutchan20-Sep-09 5:30

Richard MacCutchan

20-Sep-09 5:30

I can only speculate on this but if the statement

licenseKey = Registry.LocalMachine.CreateSubKey(@"Software\openorganise");

fails for any reason then licenseKey will be uninitialised.

Alan N20-Sep-09 8:02

Alan N

20-Sep-09 8:02

Ben Magee wrote:
OpenSubKey(@"software/openorganise");

Ben Magee wrote:
CreateSubKey(@"Software\openorganise");

Should these both be backslash?

Alan.

Ben Magee20-Sep-09 8:24

Ben Magee

20-Sep-09 8:24

Thanks for the feedback, I will look into all these issues now.

Could you please give a example of a lessthan statement in the current context im using?

thanks,
Ben.

Luc Pattyn20-Sep-09 8:34

Luc Pattyn

20-Sep-09 8:34

if (1 < 2) MesageBox("one is less than two");

Luc Pattyn

Have a look at my entry for the lean-and-mean competition; please provide comments, feedback, discussion, and don’t forget to vote for it! Thank you.

Local announcement (Antwerp region): Lange Wapper? Neen!