C# Discussion Boards - CodeProject

Access violation writing location 0x00000000

Farhan Ali6-Apr-07 1:50

6-Apr-07 1:50

Asalam o Alaikum:

I have made a desktop application in c# which gets text from the controls like textboxes.on some forms it works fine but sometime gives this error

Access violation writing location 0x00000000

how this error can be removed.

Thanx

Re: Access violation writing location 0x00000000

rp_suman6-Apr-07 2:12

rp_suman

6-Apr-07 2:12

This will happen when you assign something to a NULL pointer.
Put a break point and debug step by step. See the variable at the left of error happening line.
Best Regards,
Suman

Re: Access violation writing location 0x00000000

Farhan Ali6-Apr-07 2:22

Farhan Ali

6-Apr-07 2:22

It happens when this line executes

SendMessage(lvwHwnd, LVM_GETITEMTEXT, selectedrow, _lvi);

_lvi is the pointer which is not null it has some address.

hopefully this info will help u to answer

Thanx

Re: Access violation writing location 0x00000000

CPallini6-Apr-07 3:12

CPallini

6-Apr-07 3:12

Seems the wrong forum (C++ one is more appropriate), anyway...

you have to pass valid pointer to a valid LVITEM struct, i.e. a properly initialised struct (you have to take special care with pszText and cchTextMax members, the former must point to an allocated buffer, the latter must contain the size of the buffer itself, see MSDN [^]).

Hope that helps.

Smile | :)

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.

Re: Access violation writing location 0x00000000

Luc Pattyn6-Apr-07 4:21

Luc Pattyn

6-Apr-07 4:21

Hi,

if you happen to send a message to another process, and that message needs an address,
then that address must be valid in that process, not in the local process.

whatever, publishing the entire method (and relevant data members) may allow us
to comment.

Smile | :)

Luc Pattyn

[My Articles]

How to enerate random numbers in C#

Test2703076-Apr-07 1:26

Test270307

6-Apr-07 1:26

Hello,

I want to generate random numbers to rename files when i uploaded employees CV.
suppose first i uploaded a cv for emp1 name aa.doc i rename it a random numbers.
then i uploaded a cv for emp2 name bb.doc. but also that files i remaned it randomly.

pls help me.

thanks.

Re: How to enerate random numbers in C#

V.6-Apr-07 1:49

6-Apr-07 1:49

generate a GUID or use the Random class.

hope this helps.

V.
I found a living worth working for, but haven't found work worth living for.

Re: How to enerate random numbers in C#

CPallini6-Apr-07 1:52

CPallini

6-Apr-07 1:52

To generate random numbers, use Random class.
Not so detailed, I know, but you post wasn't that clear...
Smile | :)

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.

How to use Windbg for windows

Farhan Ali6-Apr-07 0:37

Farhan Ali

6-Apr-07 0:37

Hi;

I want to debug my application(which has been developed in c#) with Windbg.but i dont know how to use this software.
Can anybody guide me.

Thanx

Re: How to use Windbg for windows

rp_suman6-Apr-07 2:18

rp_suman

6-Apr-07 2:18

Please visit these pages:
http://www.codeproject.com/debug/windbg_part1.asp[^]
http://en.wikipedia.org/wiki/WinDbg[^]
Best Regards,
Suman

Configuration error!

Nafiseh Salmani5-Apr-07 23:55

Nafiseh Salmani

5-Apr-07 23:55

visit this address:

http://www.moshaveran.net/npc/[^]

this is a web application which i uploaded it . but how can i solve the error?!! what is it? D'Oh! | :doh:

Re: Configuration error!

SABhatti6-Apr-07 6:00

SABhatti

6-Apr-07 6:00

Have you looked and tried to follow what the error description says

It is an error to use a section registered as allowDefinition='MachineToApplication' beyond application level. This error can be caused by a virtual directory not being configured as an application in IIS.

Is the virtual directory configured as an application in IIS?

-----

GDIPlus Thread safeness

a.mulay5-Apr-07 23:34

a.mulay

5-Apr-07 23:34

Is the GDIPlus functionalty in .Net threadsafe?

e.g For Bitmap class, the MSDN states "Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe. ".

I am using the GDIPlus functionality inside .Net web services, is that safe?

Thank you,
Amit.

Help for Window Service.

blue_arc5-Apr-07 23:07

blue_arc

5-Apr-07 23:07

Hello friends ,

I have a problem with window services, actually i am new to it. and i have to complete few things.

i want my service get started as soon as system boots up. but i want it to perform any task only when any particular system event occurs..

so my question is How can i do this?

Can i add another event with apart from OnStart and OnStop

and if yes then how can i check the any perticular system event has occured..

Thanks in adv Wink | ;)

Ravi Kant Srivastava
(System Analyst)
HandsOn Technology & Engineering
Gurgaon
(India)
e-mail:ravikant@hte.co.in

Using a C++ function (defined in a dll) with char* param [modified]

jozsurf5-Apr-07 22:35

jozsurf

5-Apr-07 22:35

Hi All,

I'm reasonably new to C# and have recently been coding parts of a C# user interface which operates in tandem with a C/C++ back-end. Things have been going O.K. until I had to make use of a function, whose prototype looks like this:

int functionName (const char* param1, const char* param2, char* nastyParam)

In my C# code, I have been dealing with the const char* params by mapping them to C# strings...that has been working quite well. Now the problem with nastyParam above is the intention is for the function to (possibly) return some string value to the caller via nastyParam. The following is what I have done thus far for the function above:

...<br />
      private static extern int functionName(<br />
            [MarshalAs(UnmanagedType.LPStr)] param1,<br />
            [MarshalAs(UnmanagedType.LPStr)] param2,<br />
            [MarshalAs(UnmanagedType.LPArray)] IntPtr nastyParam);

I've been trawling the net for solutions and came across a suggestion which involved mapping the char* to a C# IntPtr (as above)...the explanation in that article made sense to me, so I gave it a go but no luck thus far.

Anyone have any ideas?

cheers!

-- modified at 4:44 Friday 6th April, 2007

Re: Using a C++ function (defined in a dll) with char* param

CPallini6-Apr-07 2:06

CPallini

6-Apr-07 2:06

Have a look here [^] (see the author's approach to GetClassName marshaling).

Hope that helps

Smile | :)

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.

Re: Using a C++ function (defined in a dll) with char* param

Luc Pattyn6-Apr-07 4:31

Luc Pattyn

6-Apr-07 4:31

Hi,

you want a StringBuilder of sufficient capacity.
And it would be safer to pass the capacity (of buffer size) as a parameter as well
(so your C/C++ function can be made safe, in order to prevent buffer overflow problems).

Smile | :)

Luc Pattyn

[My Articles]

Re: Using a C++ function (defined in a dll) with char* param

jozsurf6-Apr-07 16:46

jozsurf

6-Apr-07 16:46

Thanks guys. I'll give it a go and see how it turns out...

Re: Using a C++ function (defined in a dll) with char* param

jozsurf8-Apr-07 15:28

jozsurf

8-Apr-07 15:28

Worked beautifully. Thanks!

Webpage load

linhuu5-Apr-07 22:01

linhuu

5-Apr-07 22:01

In C# (window application), I want to download a webpage content (ex:"http://codeproject.com") how can I do?
I know about "web browser control" but I don't want to use it.
Please help me!
Thanks!

Re: Webpage load

Stefan Troschuetz5-Apr-07 23:45

Stefan Troschuetz

5-Apr-07 23:45

Take a look at the HttpWebRequest class.

"Programming today is a race between software engineers striving to build bigger and better idiot-proof programs, and the Universe trying to produce bigger and better idiots. So far, the Universe is winning." - Rick Cook

www.troschuetz.de

Re: Webpage load

Obaid ur Rehman5-Apr-07 23:49

Obaid ur Rehman

5-Apr-07 23:49

Use DownloadFile method of the System.Net.WebClient Class.

How can i make exe of my appliction?

Nekshan5-Apr-07 20:24

Nekshan

5-Apr-07 20:24

i m making a window application in dotnet c#.
How can i make exe of my appliction?
Thanking You.
Regards Nekshan.

Re: How can i make exe of my appliction?

Obaid ur Rehman5-Apr-07 20:34

Obaid ur Rehman

5-Apr-07 20:34

An executable is made whenever you compile your application. It resides in the Debug or Release folder of your project.

xml document

Tauseef A5-Apr-07 20:23

Tauseef A

5-Apr-07 20:23

hi guys

i have created a schema named evs.xsd,
now i want to create am xml document based on this schma but dont know how to do that?
any help please

hello

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