Re: Run Time Error in simple C# windows app - C# Discussion Boards

Re: Run Time Error in simple C# windows app

OriginalGriff24-Aug-10 23:46

24-Aug-10 23:46

When it says "Null reference error" it means that you are trying to refer to an object that has not been set. In this case (and assuming there is no code you missed) it would be the Parent property. Since you have used (Parent as ProjectDoc) I can only assume that the parent is not a ProjectDoc derived object.

Firstly, whenever you use as make a habit of checking the result:

MyClass mc = obj as MyClass;
if (mc != null)
   {
   ...
   }

It will save you a lot of grief later on!

Secondly, put a breakpoint on the offending line, and see what the Parent property actual is. This should tell you what you need to do.

Real men don't use instructions. They are only the manufacturers opinion on how to put the thing together.

Re: Run Time Error in simple C# windows app

Abhishrek25-Aug-10 17:34

Abhishrek

25-Aug-10 17:34

Thanks for the reply "OriginalGriff".
I knew there was something wrong, and checking for null will also tell the same.
same will the try .. catch.
However, i was looking for the solution to access myfunc in another class.
The reply by "bhiller" solved the problem.

Thanks anyway, I will keep in mind to check for null Thumbs Up | :thumbsup:

Re: Run Time Error in simple C# windows app

Bernhard Hiller25-Aug-10 0:03

Bernhard Hiller

25-Aug-10 0:03

Let us analyze the hierarchy of the elements:
You start with a form (ProjectDoc). You add a UserControl panelProjectDoc to its control, thus ProjectDoc becomes Parent of panelProjectDoc. Then you add a UserControl buildBlock to panelProjectDoc, thus panelProjectDoc becomes Parent of buildBlock. Consequently, ProjectDoc is the grand parent of buildBlock. You would need the Parent of the Parent at the position where you get the run time error.

Re: Run Time Error in simple C# windows app

Sauro Viti25-Aug-10 2:21

Sauro Viti

25-Aug-10 2:21

In other words, you should write (parent.Parent as ProjectDoc).myfunc(p)

Re: Run Time Error in simple C# windows app

Luc Pattyn25-Aug-10 2:31

Luc Pattyn

25-Aug-10 2:31

yes, if you want it to blow up in your face at the first unforeseen way of using it, that is what you do. There is another approach called defensive programming that keeps you from putting everything in one line of code.

Smile | :)

Luc Pattyn [Forum Guidelines] [Why QA sucks] [My Articles] Nil Volentibus Arduum

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Re: Run Time Error in simple C# windows app

OriginalGriff25-Aug-10 2:59

OriginalGriff

25-Aug-10 2:59

Three simple ways to fail in one line of code. Sigh | :sigh:

"But a try...catch block will fix that..." Dead | X|

Real men don't use instructions. They are only the manufacturers opinion on how to put the thing together.

Re: Run Time Error in simple C# windows app

Luc Pattyn25-Aug-10 3:16

Luc Pattyn

25-Aug-10 3:16

make sure to keep the catch block empty, no reason to alarm the user or burden the support people.

Laugh | :laugh:

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Re: Run Time Error in simple C# windows app

OriginalGriff25-Aug-10 3:23

OriginalGriff

25-Aug-10 3:23

Makes you wonder why "On Error Resume Next" never made it into the C# spec. Laugh | :laugh:

Real men don't use instructions. They are only the manufacturers opinion on how to put the thing together.

Re: Run Time Error in simple C# windows app

DaveyM6925-Aug-10 3:38

DaveyM69

25-Aug-10 3:38

I was just talking to a colleague about that following the BBC Micro post in the lounge!

Dave

If this helped, please vote & accept answer!

Binging is like googling, it just feels dirtier.
Please take your VB.NET out of our nice case sensitive forum.(Pete O'Hanlon)

BTW, in software, hope and pray is not a viable strategy. (Luc Pattyn)

Re: Run Time Error in simple C# windows app

PIEBALDconsult25-Aug-10 15:26

PIEBALDconsult

25-Aug-10 15:26

Luc Pattyn wrote:
in one line of code

What's a line of code?

MyType x = y as MyType ; if ( x != null ) { x.foo() ; x.bar() ; } else { something.else() ; } ...

Re: Run Time Error in simple C# windows app

Luc Pattyn25-Aug-10 15:32

Luc Pattyn

25-Aug-10 15:32

you discovered the space bar now? usually you have a newline where we put a space...

Smile | :)

Luc Pattyn [Forum Guidelines] [Why QA sucks] [My Articles] Nil Volentibus Arduum

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Re: Run Time Error in simple C# windows app

PIEBALDconsult25-Aug-10 18:44

PIEBALDconsult

25-Aug-10 18:44

Yes, just more proof that (in the C family of languages) spaces and newlines are interchangable and generally unimportant (to the compiler).

Re: Run Time Error in simple C# windows app

Abhishrek25-Aug-10 17:20

Abhishrek

25-Aug-10 17:20

Thank you Sauro Viti.
That worked !!! Thumbs Up | :thumbsup:

Re: Run Time Error in simple C# windows app

Abhishrek25-Aug-10 17:22

Abhishrek

25-Aug-10 17:22

Thank you for explaining.
I got your point.
and the code from "Sauro Viti" worked fine Smile | :)

What is the best way to do Clone to class that derived from Queue ( code attached )

Yanshof24-Aug-10 23:07

Yanshof

24-Aug-10 23:07

I have some class that derived from class queue ( generic namespace ) and i need to implement the IConable Interface.
Each object on the queue is implament the IClonable interface also.

Im not sure that my clone impementation of the queue derived class is the right way ...

The code:

<code>

public object Clone()
        {
            derivedFromQueueCollection retCollection = new derivedFromQueueCollection();

            lock( this )
            {
                ObjectOnQueue[] arr = ToArray();
                for( Int32 i = arr.Length ; i > 0 ; i-- )
                {
                    retCollection.Enqueue( arr[ i ].Clone() as ObjectOnQueue);
                }
            }

            return retCollection;
        }

</code>

modified on Wednesday, August 25, 2010 9:36 AM

Re: What is the best way to do Clone to class that derived from Queue ( code attached )

Eddy Vluggen25-Aug-10 7:43

Eddy Vluggen

25-Aug-10 7:43

Looks good to me Thumbs Up | :thumbsup:

Returning a new Queue, populated with clones of the original Queue. You even used the CTS-compliant integer, as opposed to the language-specific alias Smile | :)

I are Troll Suspicious | :suss:

Message Removed

24-Aug-10 22:10

Subrat Patnaik

24-Aug-10 22:10

Message Removed

Please delete your other posts on this.

Pete O'Hanlon24-Aug-10 22:18

Pete O'Hanlon

24-Aug-10 22:18

Rather than having the same question asked 3 times, why not stick with 1?

I have CDO, it's OCD with the letters in the right order; just as they ruddy well should be

My blog | My articles | MoXAML PowerToys | Onyx

Message Removed

24-Aug-10 23:24

Subrat Patnaik

24-Aug-10 23:24

Message Removed

Re: Please delete your other posts on this.

R. Giskard Reventlov24-Aug-10 23:42

R. Giskard Reventlov

24-Aug-10 23:42

and you probably won't until you tidy up all of your duplicate posts!

"If you think it's expensive to hire a professional to do the job, wait until you hire an amateur." Red Adair.
nils illegitimus carborundum

me, me, me

Re: Please delete your other posts on this.

OriginalGriff25-Aug-10 1:20

OriginalGriff

25-Aug-10 1:20

I'm sorry, but the answer today[^] is INFEASIBLE

Real men don't use instructions. They are only the manufacturers opinion on how to put the thing together.

Re: Please delete your other posts on this.

Luc Pattyn25-Aug-10 1:48

Luc Pattyn

25-Aug-10 1:48

Yeah, the answer cannot always be complimentary, can it?

Smile | :)

Luc Pattyn [Forum Guidelines] [Why QA sucks] [My Articles] Nil Volentibus Arduum

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Re: Please delete your other posts on this.

OriginalGriff25-Aug-10 1:52

OriginalGriff

25-Aug-10 1:52

Well spotted! Thumbs Up | :thumbsup:

Real men don't use instructions. They are only the manufacturers opinion on how to put the thing together.

code for instal my font to client machine when my setup run

Member 274894524-Aug-10 20:07

Member 2748945

24-Aug-10 20:07

c# code for instal my font to client machine when my setup run

SuresPanneer

Re: code for instal my font to client machine when my setup run

phil.o24-Aug-10 20:41

phil.o

24-Aug-10 20:41

That has been told many times, but I'll still give you the link to read the guidelines of these forums :

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