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There is also an "UnhandledException" delegate in the Application class that you should assign your handler to.
The difficult we do right away...
...the impossible takes slightly longer.
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Does anyone have any code for CRC8 calculation and polynomial calculation?
I'm trying to learn about this and having code to see it works would really help me.
Thank you.
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CodeProject is your friend: "C# CCITT-8 CRC Algorithm:" [^].
There are three other articles on CRC8 on CodeProject: just search for them.
« There is only one difference between a madman and me. The madman thinks he is sane. I know I am mad. » Salvador Dali
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If you found the CodeProject implementation, you can always ask questions on the article forum. That's what it's there for.
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If someone could help me with this example [^] I would really appreciate that.
I'm not sure how to get it working, or why the author used "1, 2, 3" in the example. I would like to pass hex values.
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turbosupramk3 wrote: I had some trouble with them and wanted to be able to ask questions so I posted here.
Well, why aren't you asking specific questions based on the difficulties you are having with working with codes in the resources you found ?
We can't read your mind, and, in general, the more specific the question is, here, the more likely the poster is to get a satisfying answer, quickly.
Of course, if you are working with complex code you didn't write yourself, you may be getting error messages, or crashes, as you attempt to modify/use the code, and, possibly, only the author of the resource may be able to help you. In the case of CP articles/resources, as Pete points out, you can post a question to the author.
« There is only one difference between a madman and me. The madman thinks he is sane. I know I am mad. » Salvador Dali
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Hi Bill. I would have asked specific questions in the first post had someone replied with a code example.
If you'll notice that after it was determined that no one had an example they wrote or used frequently, I started to ask specific questions about a link/piece of code I had found on the internet and was hoping to build from that.
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hi
i will insert info person to database and i use janus control and bind all input from databinding and bind picturebox and mathimage that is editbox
and in run accure error:
Update requires a valid UpdateCommand when passed DataRow collection with modified rows
my code:
save:
try
{
bimehgozarBindingSource.EndEdit();
bimehgozarTableAdapter.Update(this.bimehDataSet.bimehgozar);
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
}
new:
bimehgozarBindingSource.AddNew();
string query = "SELECT MAX(code_bg) FROM bimehgozar";
SqlConnection con = new SqlConnection("Data Source=.;Initial Catalog=bimeh;Integrated Security=True");
SqlCommand comSelect = new SqlCommand(query, con);
con.Open();
string ID = comSelect.ExecuteScalar().ToString();
if (ID == "")
editBox8.Text = 1.ToString();
else
{
int a = Convert.ToInt32(ID);
a = a + 1;
editBox8.Text = a.ToString();
}
editBox1.Text = "";
editBox2.Text = "";
editBox3.Text = "";
editBox4.Text = "";
editBox5.Text = "";
editBox6.Text = "";
editBox7.Text = "";
editBox11.Text = "";
editBox12.Text = "";
editBox13.Text = "";
editBox14.Text = "";
pictureBox1.Image = null;
i am accure errore in save Button click
please help me i am tired. how save image when use janus control beacuse i use janus control not have value for insert.
wheather i need to convert image to array.
please guide me i want to insert info and long time accure error.
best regards
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If you have a problem with Janus control, perhaps you need to contact the support forums for the people who wrote it. They will be the best placed to answer questions like this.
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thanks i put my question in many forum of programing but i just now
my question in janus forum.
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hello,
I developed a C # application I am connecting to the database , when I do a simple query the application launches and data are collected in the datagridview . but when I want to retrieve a lot of data and I run I click run the windows form does not appear and nothing appears .
Thank you 
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Well then ... don't do that! ("read a lot of data").
Use virtualization.
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I have to retrieve a lot of data on my datagridview
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You have 5 possible choices.
1) Use Virutalization on the DataGridView and only retrieve the records that are being displayed.
2) Use Virtualization...
3) Use Virtualization...
4) Use Virtualization...
5) Put up with the situation you have because the long part of this process is more than likely the number of rows you're trying to stuff into the grid, not the speed of the retrieval of those rows. As a rule of thumb, it takes 10 times longer to get the grid to show the data than it does to retrieve it.
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is that you have a tutorial to use virtualization?
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Google for "C# DataGridView Virtualization"
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Do you really? How much is a lot? Have you checked with your users that they want to see all that data in one go? You'll be surprised at how little users really want to wade through screens of data.
If you must retrieve it all in one go though, retrieve it on a background thread, and then marshal the data back onto the UI thread.
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how to do a background thread , and then collect the data back to the UI thread .
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The easiest way to get started with this is to use something called the Task Parallel Library. Have a search here on CodeProject for Sacha Barber's articles on it; that should get you started.
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Can you be more specific? What do you mean with "lots of data" ? 10 000 records, 100 000? 1 000 000?
Secondly is it working in debug and not in release or does it work, but when you click (a button?) the form dissapears? Do you get an error message? ...
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hi,
a lot of data 1000000, there is no error the application takes too long to display (3hours).
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all righty, that's already more clear.
First of all, 1 000 000 records in one go is just a big NO.
As an exercise calculate the size (in bytes) of one record and multiply that by 10^6. That amount of data is transferred through the wire... In addition your objects in code will also be too large memory wise.
Your best bet is to fetch this stuff in bits and parts. The first idea that comes to mind is to use paging, although for a million records this still a 1000 pages of a 1000 records.
In addition to that paging you'll need to filter the data to what users would like to see. You start with an empty grid and allow the user to filter on several columns before fetching anything.
3 hours is a long time. Make sure the query is optimized and the indexes on the database are properly built.
You'll probably need to fiddle with both the code part and the database in order to come to a good solution.
As rule of thumb any collection larger then let's say 10 000 is a no go. (I'm talking normal records, not blobs with huge amounts of data). (This number is not a rule, 100 can be already too much and in some cases 50 000 can still work ok)
This is not a simple problem, take your time to handle it right.
Hope this helps.
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hello :
I am trying to develop an application in C # I made my connection string to connect to the database but when I launch an error message saying : An unhandled exception of type ' System.InvalidOperationException exception 'occurred in System.Data.dll
Additional information: ExecuteNonQuery : the Connection property has not been initialized.
Thank you 
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The error is pretty explicit:
the Connection property has not been initialized.
So look at your code: check that you have created an SqlConnection object using the correct connection string, that you have opened the connection, and that you have attached it to the SqlCommand:
using (SqlConnection con = new SqlConnection(strConnect))
{
con.Open();
using (SqlCommand cmd = new SqlCommand("SELECT iD, description FROM myTable", con))
{
using (SqlDataReader reader = cmd.ExecuteReader())
{
while (reader.Read())
{
int id = (int) reader["iD"];
string desc = (string) reader["description"];
Console.WriteLine("ID: {0}\n {1}", iD, desc);
}
}
}
}
Bad command or file name. Bad, bad command! Sit! Stay! Staaaay...
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