Crystal Reports Gurus - need help - please - C# Discussion Boards

How do I Marshal Vector using Pinvoke

9-Jul-07 7:12

Hi,

sorting a DataGridView is no different than sorting any other collection:
- they have a Sort() method that applies a default sort order
- they have a Sort(IComparer) method that takes an object capable of
comparing two objects of the type you want to get sorted.
So read up on IComparer, and provide a little class that inherits from it.

The world must be full of examples of this.

Smile | :)

Luc Pattyn

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catch { [Google] }

Subodh Borker9-Jul-07 4:41

Subodh Borker

9-Jul-07 4:41

Hi All,

I want to pass a vector from a C++ DLL to a .Net Client, can any one help me on how do i Marshal a vector using Pinvoke, I dint found any article related to this on the net.

The vector i want to pass is a vector of user defined structures

Regards,
Subodh

Crystal Reports Gurus - need help - please

Rome'9-Jul-07 4:27

Rome'

9-Jul-07 4:27

Calling all Crystal Report Gurus

I have this strange error coming up in one of my reports.

"One or more fields could not be found in the result set. Use verify Database to update report. Error in file ---------------- . the rowset column could not be found."

this is one of the last reports in my app and the delivery is delayed on account of this error.

There doesn't seem to be any apparent reason for this error.

Let me give you guys the background

1. I am using Visual studio 2005 and the CR verson which comes bundled with it.
2. I am using a CR viewer and the report source is an Reportdocument object
3. I have a record selection formula

as follows

if {?ClientSelect} = 'All' then true else {InvoiceSaleAnalysis;1.ClientID}={?ClientID}

I am setting the values of the above params thru front end code

When I view the report with 'All' (default it shows ok. However when i select a particular ClientID and change the param and refresh the report it gives me the above error the first time and when i refresh it again the required report is displayed

any ideas would be of help

Romi

Udp client Programming

ramdil9-Jul-07 3:57

9-Jul-07 3:57

Hi all.
I have created an application which access a send and receive method written in a class

now the problem which i am facing is strange when i call the recieve method of udp client object , and then if i want to stop the code of my application, it is not closing properly..when i checked ,,i found that recieve method of udp client creates all the problem.is there any way to play around..or any one can help me where i can found a good code for receiving...the main thing is that recieve method of udpclient should be always be listening...it should be in continous loop..

pls help me..

Regards
DilipRam

Jimmanuel9-Jul-07 4:18

9-Jul-07 4:18

I had a similar situation not too long ago. To solve the problem I used the following snippet in a separate thread; to close the port just set UDPrunning to false, wait for the thread to exit and then you can close the port. I'm not sure if it's the best solution, but it is a solution that worked in my situation.

while (UDPrunning == true)
{
    if (udpSocket.Available > 0)
    {
        try
        {
            IPEndPoint msgSenderInfo = new IPEndPoint(IPAddress.Any, 0);
            Byte[] incomingData = udpSocket.Receive(ref msgSenderInfo);
            // do something with the data
        }
        catch (SocketException e)
        {
            // do something to handle the exception
        }
    }
    else
    {
        // Stop the thread from using too much processor time
        Thread.Sleep(100);
    }
}

ramdil9-Jul-07 4:41

9-Jul-07 4:41

Hi thanks for the reply
But i have doubt regarding one of ur suggestions.
You comment was
"to close the port just set UDPrunning to false, wait for the thread to exit and then you can close the port"

here the variable UDP running i have set to false in the close event of my application.and after seting the variable i am closing the port..is this the what you meant...if it is then no problem but i got confused that you were speaking abt the wait for the thread how should i wait for thread..
can you pls explain.

Regards
DilipRam

Jimmanuel9-Jul-07 4:52

9-Jul-07 4:52

That's exactly what I meant! To stop listening all you have to so is set that var to false and continue on your way.

The comment about waiting for the thread is because I was running that method in a separate Thread from the gui thread. When I was shutting down my gui I wanted to make sure that the listener thread exited so that it wouldn't hang up my application. The Thread.Join() method waits for a thread to exit, so my socket shutdown code looked like this:

UDPrunning = false;
udpSocketThread.Join();
udpSocket.Close();

Luc Pattyn9-Jul-07 5:05

9-Jul-07 5:05

Hi,

I would not like a Join in my closing code, it might sit and wait forever.
Isnt the essence of the problem that you want the UDP listener thread to be
a background thread, one that does not prevent your app from exiting ?

Smile | :)

Luc Pattyn

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ramdil9-Jul-07 5:12

9-Jul-07 5:12

Hi

can you bit clear please as i am new this socket programming and any way i am calling the receive method in a thread...

Regards
DilipRam

Jimmanuel9-Jul-07 5:20

Re: Disconnecting your Ethernet may keep your app alive !

9-Jul-07 5:20

That essentially was the idea but there are 2 reasons that I didn't set udpSocketThread.IsBackground = true; and forget about it:

1) The worker function is coded to avoid a blocking situation where the thread would hang so I wasn't worried about it waiting forever and
2) I didn't previously know about the Background vs. Foreground Thread property. That's a pretty nifty Property to have, thanks for the info!

Smile | :)

Luc Pattyn9-Jul-07 5:56

Re: Disconnecting your Ethernet may keep your app alive !

9-Jul-07 5:56

Yes, but my point is when the listener is in its Receive() method, it needs
another packet to resume its course, and only after that it could exit the loop,
so your Join() is actually waiting for another UDP packet to arrive (which
may never happen).

Smile | :)

Luc Pattyn

try { [Search CP Articles] [Search CP Forums] [Forum Guidelines] [My Articles] }
catch { [Google] }

Jimmanuel9-Jul-07 6:34

9-Jul-07 6:34

In my situation I wasn't worried about the Ethernet cable being pulled. It was just a little test app connecting to a server on the local machine as a proof-of-concept of another piece of code. That's why I said in my original post "I'm not sure if it's the best solution, but it is a solution that worked in my situation."

Using IsBackground would have been a wiser choice had I known about it.

ramdil9-Jul-07 5:14

9-Jul-07 5:14

Thanks for the reply..
just want to confirm that the join method will not get into any hang mode.
because i am calling the stop method by creating a object of dll and i dont have a thread in my application but the thread is present in dll where i have written the recieve method...

Regards
DilipRam

Jimmanuel9-Jul-07 5:23

9-Jul-07 5:23

See my reply to Lucs post. I just found this[^] article explaining background vs. foreground threads, so apparently if you set udpSocketThread.IsBackground = true; then you won't ever have to worry about Joining the thread.

ramdil9-Jul-07 5:38

9-Jul-07 5:38

Thanks again and sorry for troubling again.just to ensure
that instead of doing UdpListnerThread.Join(); in my stop method
i need to set udpSocketThread.IsBackground = true.is that it means

thanks

Regards
DilipRam

Luc Pattyn9-Jul-07 5:56

9-Jul-07 5:56

That's how I would do it anyway.

Smile | :)

Luc Pattyn

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ramdil9-Jul-07 22:02

9-Jul-07 22:02

Thanks for replies..finally my stop method will be having the following code
since i am using two udps and thread name is
udpManagerbroadCast.Close();///..udp
UdpListnerThread.IsBackground = true;///..thread
FlagVal = true;///flag value
soUdp.Close();///..udp

and hope this is what you all were suggesting.Hope this fit the standards which you were suggesting

Regards
DilipRam

Jimmanuel9-Jul-07 6:36