C# Discussion Boards - CodeProject

Migounette14-Dec-09 23:02

14-Dec-09 23:02

In fact you can have a simple to a more complete solution...

Parsing grammar is based on definitions, for instance BNF, ABNF...
In your case, you can write a simple peace of code in order to have your expression parsed.

But if you want to have a more complexe handling use this pointer and check the section 7.2

[^]

Please update us.

Alan Balkany15-Dec-09 3:59

Alan Balkany

15-Dec-09 3:59

One approach is to put the expression in a binary tree with numbers (or variables) at the leaves and operators at the interior nodes. Replace higher-precedence operators (and parenthesized expressions) with subtrees first.

To evaluate, do a postorder traversal, applying the operator at each interior node to the values obtained from its two subtrees.

When you're done, the result will be in the root node.

PIEBALDconsult15-Dec-09 4:37

PIEBALDconsult

15-Dec-09 4:37

Hmmm... looks like a teacher assigned an RPN assignment yesterday.

See my response here[^].

BillWoodruff15-Dec-09 11:01

BillWoodruff

15-Dec-09 11:01

I think without explicity declaring the order of precedence of operator execution ... i.e. : is this infix, postfix, RPN ? ... you cannot begin to respond to this question.

There are some math expression "parser" articles around CodeProject; try this one : [^].

best, Bill

"Many : not conversant with mathematical studies, imagine that because it [the Analytical Engine] is to give results in numerical notation, its processes must consequently be arithmetical, numerical, rather than algebraical and analytical. This is an error. The engine can arrange and combine numerical quantities as if they were letters or any other general symbols; and it fact it might bring out its results in algebraical notation, were provisions made accordingly." Ada, Countess Lovelace, 1844

DataGridView Delete Slow

stancrm14-Dec-09 22:36

stancrm

14-Dec-09 22:36

Hello.

I have a DataGridView with 3 Columns and 100000 Rows.
If I select all rows and press "Del" keys from keyboard,
then it takes too long to delete all of them.
Are there anyways to improve the performance ?

Thanks.

Eddy Vluggen14-Dec-09 22:47

Eddy Vluggen

14-Dec-09 22:47

The grid is updating, and repainting. A lot Smile | :)

You can temporarily disable drawing using the SuspendLayout[^] method, and turn it back on using ResumeLayout.

I are Troll Suspicious | :suss:

Migounette14-Dec-09 22:56

14-Dec-09 22:56

In fact the suspend layout will not help on this issue.
You must use a virtual mode in order to avoid such redraw issue.

Look at this all is in....

[^]

Eddy Vluggen15-Dec-09 0:16

Eddy Vluggen

15-Dec-09 0:16

Migounette wrote:
In fact the suspend layout will not help on this issue.

I had to check to verify that, and it seems that you are right.

+5 Smile | :)

I are Troll Suspicious | :suss:

SEHException was unhandled External component has thrown an exception

Ashfield14-Dec-09 23:45

Ashfield

14-Dec-09 23:45

Perhaps setting the datasource to null and deleting the actual data on a background thread would help?

Alternatively, why put 100,000 rows in a datagrid, nobody will scroll through them all, so filter before load?

Bob
Ashfield Consultants Ltd
Proud to be a 2009 Code Project MVP

Xelalem14-Dec-09 22:07

Xelalem

14-Dec-09 22:07

i was tring to write some data to the parallel port using inpout32.dll but i keep getting this exception

SEHException was unhandled:
External component has thrown an exception
this is the code i used

class PortAccess
      {

         [DllImport("inpout32.dll", EntryPoint = "Out32")]
         public static extern void Output(int adress, int value);
      }

public void OUT()
{
PortAccess.Output(888, 1);
}

am i doing something wrong or wat?

Re: SEHException was unhandled External component has thrown an exception

Migounette14-Dec-09 22:51

Re: SEHException was unhandled External component has thrown an exception

14-Dec-09 22:51

It may be several problems, but it appears to be an issue with the access of the library or the port.

Which OS are you running ?

More over add this to your main app in order to get the information, please update us.

[STAThread]
static void Main(string[] cmdLine)
{

try
{
Application.ThreadException += ApplicationThreadException;
Application.SetUnhandledExceptionMode(UnhandledExceptionMode.CatchException);
...
}
catch (Exception exception)
{
...
}
finally
{
...
}

}

Xelalem15-Dec-09 0:30

Xelalem

15-Dec-09 0:30

tnx 4 ur reply..
I am using WindowsXp SP2. and i posted only some part of the code, it is a windows form application on visiual studio 2008.

i called the PortAccess.output function on a button click event. every thing works fine until i click the button

Re: SEHException was unhandled External component has thrown an exception

Migounette15-Dec-09 4:23

Re: SEHException was unhandled External component has thrown an exception

15-Dec-09 4:23

did you try to add the global exception catch and dump its message

Xelalem15-Dec-09 4:33

Xelalem

15-Dec-09 4:33

thanks but i got the solution. i download the updated INPOUT32.dll from http://www.logix4u.com and it worked

Re: SEHException was unhandled External component has thrown an exception

gsuspradeep18-Dec-09 8:40

gsuspradeep

18-Dec-09 8:40

pls provide the same DLL to me...

Re: SEHException was unhandled External component has thrown an exception

DavidKoganti28-Jul-11 4:13

DavidKoganti

28-Jul-11 4:13

THE SEHException is really nasty to debug. Because it comes from the COM.

I was able to resolve this nasty bug only by uninstalling .NET 3.5 SP1 and reinstalling again. Because I use windows 7 I had to do this from my windows add/remove components section.

Others suggestions like reseting IIS failed.

VJ Koganti
http://www.PrintersRose.com/

Encrypting & decrypta txt file

3bood.ghzawi14-Dec-09 21:14

3bood.ghzawi

14-Dec-09 21:14

Hi all...
I'm asking of how i can encrypt and decript a txt file using C#,
i think u don't mined to help me ...
Thank u...............
Big Grin | :-D

Blue_Boy14-Dec-09 21:16

Blue_Boy

14-Dec-09 21:16

Have you search on google?[^]

I Love T-SQL
"Don't torture yourself,let the life to do it for you."
If my post helps you kindly save my time by voting my post.

www.aktualiteti.com

Re: Encrypting & decrypta txt file [modified]

hamed-vojdani18-Dec-09 7:53

hamed-vojdani

18-Dec-09 7:53

because you want both Encrypting and Decrypting I would offer you gunzipstream

public string Decode()
{
    FileStream fs = new FileStream(Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments) + "\\MyFile.dat", FileMode.Open, FileAccess.ReadWrite);
    byte[] array = new byte[400];
    GZipStream gstream = new GZipStream(fs, CompressionMode.Decompress);
    gstream.Read(array, 0, array.Length);
    gstream.Close();
    string Mytext = Encoding.UTF8.GetString(array);
    return Mytext;
}

public void Encode(string text)
{
    byte[] array = Encoding.UTF8.GetBytes(text);
    FileStream fs = new FileStream(Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments) + "\\MyFile.dat", FileMode.Create, FileAccess.ReadWrite);
    GZipStream gstream = new GZipStream(fs, CompressionMode.Compress);
    gstream.Write(array, 0, array.Length);
    gstream.Flush();
    gstream.Close();
}

note: this solution is not completely secure!

robbrad21-Dec-09 4:32

Re: Encrypting & decrypta txt file [modified]

21-Dec-09 4:32

Hi,

How could you make this happen on the click of a button? I've tried adding it to the event but the Public void Encode(string text) line obviously stops this happening.

edit: Some of my terminology may not be correct, so if your unsure, just ask.

modified on Monday, December 21, 2009 10:41 AM

hamed-vojdani22-Dec-09 2:24

hamed-vojdani

22-Dec-09 2:24

just insert button on the form and double click it, Then
write button1_Click event code like shown.

In this sample I encoded text of TextBox1 to 'Myfile.dat' in My Document

note: must copy Encode function to Form class

private void button1_Click(object sender, EventArgs e)
{
    Encode(TextBox1.Text);
}

public void Encode(string text)
{
    byte[] array = Encoding.UTF8.GetBytes(text);
    FileStream fs = new FileStream(Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments) + "\\MyFile.dat", FileMode.Create, FileAccess.ReadWrite);
    GZipStream gstream = new GZipStream(fs, CompressionMode.Compress);
    gstream.Write(array, 0, array.Length);
    gstream.Flush();
    gstream.Close();
}

modified on Thursday, December 24, 2009 10:23 AM

robbrad22-Dec-09 2:57

22-Dec-09 2:57

I get the following error when my code is run: "The given path's format is not supported."

The error is in this line:

FileStream fs = new FileStream(Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments) + "MYFILE.txt", FileMode.Create, FileAccess.ReadWrite);

It cant be a problem with my txt file i dont think, because i have used them before in my programs and they have worked fine. Any help would be appreciated.

Extra information:
- Using VS 2008
- .NET Framework 3.5 SP1

hamed-vojdani24-Dec-09 4:27

hamed-vojdani

24-Dec-09 4:27

thanks

you forget the "\\" before "MYFILE.txt"
corrct that to this:

FileStream fs = new FileStream(Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments) + "\\MYFILE.txt", FileMode.Create, FileAccess.ReadWrite);

robbrad25-Jan-10 4:30

25-Jan-10 4:30

Thanks for your help so far. Just 1 more question. Ive managed to succesfully encrypt the data that is inputted into textbox1, but decoding it fails.

 public Form1()
        {
            InitializeComponent();
            Decode();
        }
private void button2_Click(object sender, EventArgs e)

        {
            Decode();

            StreamReader rb = new StreamReader("C:\\file.txt");
            MessageBox.Show(rb.ReadToEnd());
            rb.Close();
            
        }
            public string Decode()
        {
            FileStream fs = new FileStream(Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments) + "\\file.txt", FileMode.Open, FileAccess.ReadWrite);
            byte[] array = new byte[400];
            GZipStream gstream = new GZipStream(fs, CompressionMode.Decompress);
            gstream.Read(array, 0, array.Length);
            gstream.Close();
            string Mytext = Encoding.UTF8.GetString(array);
            return Mytext;
        }

It doesnt return any errors, it just clears the file.

Any help would be appreciated

robbrad26-Jan-10 3:16