Forum Visual C# General

Free book: No Bugs!

Sun, 29 Nov 2009 02:49:00 Z

I wrote this book in what now looks like the dawn of antiquity. I was on the Windows 95 development team at the time – C++ was still new, we still wrote the time critical parts in assembler, and Java was a word for coffee. It was a challenging world back then. Not better than today, not worse – but different challenges.

I went back and looked at what I wrote. A lot of it is specific to C, C++, and assembler. Some of it is specific to the state of the industry at that time. And those parts will only be of interest to a few with a large degree of curiosity about that time. A bit more will be of interest to people still writing C++ in an unmanaged environment.

But the first two chapters, those are still every bit as relevant today as they were when the book was written. I think most developers can be well served by reading this as it takes a philosophical look at how to write code with fewer bugs.

You can download the entire book for free at No Bugs! You may forward the free copy to friends, post it on your own website, etc. Below is a short excerpt from chapters 1 & 2 if you want a peek before downloading.

One interesting note, in chapter 2 it declares bugs should be called Massive ____ Ups. The use of the F word had to be approved by a Vice President at the publisher and I think to this day No Bugs! Remains the one programming book from a major publisher where the word appears.

download No Bugs!

Windward Reports - World's Greatest SharePoint Reporting & DocGen

filter

Sun, 29 Nov 2009 12:43:16 Z

hi how do i act the rowfilter to have the autocomplete textbox feature?

   private void txtCodeSearch_TextChanged(object sender, EventArgs e)
        { 
dv.RowFilter =" Operations like '"+ txtCodeSearch.Text+"%'";

i tried this above, but it canot fulfill the needs of my requirement.

given the sample,

111

1122

abc

matthew

when i type in 1 in the textbox, it should filter those data without the 1 infront. left with just 111, 1122

alain

How to pass data from form1 to form2?

Sat, 28 Nov 2009 02:16:41 Z

Got a problem in passing a value from form1's textbox to form2's textbox.
By the way i am using mysql connection.

Can someone help me? :) thanks

shorten my code

Sat, 28 Nov 2009 13:16:41 Z

hi how do i shorten this junk of code

   private void toolStrip_Operation_Click(object sender, EventArgs e)
        {
            OperationForm limo = new OperationForm();
            toolStripContainer1.ContentPanel.Controls.Clear();
            toolStripContainer1.ContentPanel.Controls.Add(limo);
            limo.Dock = DockStyle.Fill;
        }

into seomthing like this below?

  private void toolStrip_Operation_Click(object sender, EventArgs e)
        {
            OperationForm limo = new OperationForm();
            OpenForm(limo);
        }

        private void OpenForm(object sender)
        {
            toolStripContainer1.ContentPanel.Controls.Clear();
            toolStripContainer1.ContentPanel.Controls.Add(sender);
            sender = DockStyle.Fill;
        }

this is because i need to reuse this code for my others toolstrip

alain

Disable windows hotkeys, C#

Sun, 29 Nov 2009 10:23:11 Z

Hello!

I am developing a full screen mode application, where all windows hotkeys that exit application from full screen, need to be disabled. I could disable ALT+TAB, ALT+F4 and ALT+ESC using the following code I found in the internet:

namespace

 MyNamespace
{
 public
 partial
 class
 MainForm : Form
    {
    #region
 Dynamic Link Library Imports
    [DllImport("user32.dll"
)]
    private
 static
 extern
 int
 RegisterHotKey

(IntPtr hwnd, int
 id, int
 fsModifiers, int
 vk);
    [DllImport("user32.dll"
)]
    private
 static
 extern
 int
 UnregisterHotKey

(IntPtr hwnd, int
 id);
    #endregion



    #region
 Modifier Constants and Variables
// Constants for modifier keys


    private
 const
 int
 USE_ALT = 1;
    private
 const
 int
 USE_CTRL = 2;
    private
 const
 int
 USE_SHIFT = 4;
    private
 const
 int
 USE_WIN = 8;
        

    // Hot key ID tracker

    short
 mHotKeyId = 0;
    #endregion



    public
 MainForm()
        {
            InitializeComponent();
            RegisterGlobalHotKey(Keys.Tab, USE_ALT);    //Block Alt+TAB

            RegisterGlobalHotKey(Keys.F4, USE_ALT);    //Block Alt+F4

            RegisterGlobalHotKey(Keys.Escape, USE_ALT);//Block Alt+ESC<br/>

        }

        private
 void
 RegisterGlobalHotKey

(Keys hotkey, int
 modifiers)
        {
            try

            {
                // increment the hot key value - we are just identifying

                // them with a sequential number since we have multiples

                mHotKeyId++;

                if
 (mHotKeyId > 0)
                {
                    // register the hot key combination

                    if
 (RegisterHotKey(this
.Handle, mHotKeyId, modifiers,
                        Convert.ToInt16(hotkey)) == 0)
                    {
                        // tell the user which combination failed to register 

                        // this is useful to you, not an end user; the user

                        // should never see this application run

                        MessageBox.Show("Error: "
 +
                            mHotKeyId.ToString()  + " - "
 +
                            Marshal.GetLastWin32Error().ToString(),
                            "Hot Key Registration"
);
                    }
                }
            }
            catch

            {
                // clean up if hotkey registration failed -

                // nothing works if it fails

                UnregisterGlobalHotKey();
            }
        }

        private
 void
 UnregisterGlobalHotKey()
        {
            // loop through each hotkey id and

            // disable it


            for
 (int
 i = 0; i < mHotKeyId; i++)
            {
                UnregisterHotKey(this
.Handle, i);
            }
        }
//rest of user code

    }
}

I need to disable CTR+ESC and the Windows key (right and left). I called the RegisterGlobalHotKey function as below:

RegisterGlobalHotKey(Keys.Escape, USE_CTRL);
RegisterGlobalHotKey(Keys.None, USE_WIN);

The build is succesfull, but when programm runs I get an error, because the code enters the if (RegisterHotKey(this.Handle, mHotKeyId, modifiers, Convert.ToInt16(hotkey)) == 0) section in the RegisterGlobalHotKey() function.

My questions are:
1. Why do I get an error with CTRL+ESC and not with ALT+ESC? How can I disable the Win key using RegisterGlobalHotKey() function call?
2. Can this function be called, so that 3-key combinations like CTRL+ALT+ESC can also be disabled?
3. Are there any other hotkeys combinations that exit user from full screen?

this failed in my rowfilter

Sun, 29 Nov 2009 10:07:59 Z

Hi, i tried to perform a rowfilter with datetime below but was told that canot use the convert function in rowfilter.
the date column has the full datetime value e.g. 11/29/2009 5:36:15 PM
i want to perform rowfilter to filter only today date. please advice

dv = operation.SelectAll().DefaultView;
dv.RowFilter =

"convert(varchar,Date, 101) = '#" + DateTime.Now.ToShortDateString() + "#' ";

alain

I need to intialize an object only once, hwo do i do this?

Sun, 29 Nov 2009 09:47:32 Z

Hi Friend,

I have a default constructor of the class applicant that initializes an and DataAdapter to a table

as:

public class Applicant



{



      tblApplicantsTableAdapter daApplicants; 







     public Applicant()



     {



          daApplicants = new tblApplicantsTableAdapter();



     }     



}

In the Applicant class i have a I have MakeInstance method that should create an Applicant object as:

public List<Applicant> MakeInstances(int iInstanceCount)



{
      List<Applicant> obCollecttion = new List<Applicant>();
     for(int i = 1; i <= iInstanceCount; i++)     {



       Applicant appObj = new Applicant();



       obCollection.add(appObj);     }



}

The problem is if i create an object of Applcant using the defualt costructor for each instace it will create an instance dataadapter. But i want each object of applicant class to use only one instance of the dataadapter. How do i do this?

thanks

I'ved got to bind the data from my datagridview to textbox.Text, but it seems the application is doing a delay when i select data from datagridview very fast..

Sat, 28 Nov 2009 01:30:00 Z

The problem is there is a delay of sometimes it couldn't catch up what i am selecting. Can someone help me? :)

Here is my code.

if (dataGridViewCustomer.SelectedRows.Count != 0)
            {
                textBox1.Text = Convert.ToString( dataGridViewCustomer.SelectedRows[0].Cells[1].Value );
                dataGridViewCustomer.Update();
                         
            }

Am i missing something? or is this a limitation from c#? hmm

How to play incomplete media file

Sun, 29 Nov 2009 06:35:02 Z

Hi,

I'm using BinaryWriter to write a video/audio to disk and want to play the file while it's being written. I have checked that the completed file is working. WMP doesn't seem to want to open it until it final.

This is what i'm doing.

fs = new FileStream(@"D:\\tst.avi", FileMode.CreateNew, FileAccess.Write, FileShare.Read);

bw = new BinaryWriter(fs);

I've tried waiting for some time but still no luck.

Any help would be great.

new to .net and c#

Bitmap handling of 16bit gray tiff image

Sun, 29 Nov 2009 05:27:01 Z

I'm quite annoyed by Bitmap reading a 16 bit gray tiff image. When I do new Bitmap(filename), I get PixelFormat being Format32bppArgb and I get a black image.

Is there any way to get Bitmap translated exactly what the original one is, i.e. getting Format16bppGrayScale?

Thank you.

Problem setting accept button.

Tue, 24 Nov 2009 21:15:51 Z

I am trying to set the accept button on a form that is shown via a public static method. Right now the accept button is always stays at the first of five buttons.

        public static string ShowBox(string txtMessage, string txtTitle)
        {            
            newMessageBox = new MyMessageBox();
            newMessageBox.AcceptButton = newMessageBox.Btn3;
            newMessageBox.label1.Text = txtMessage;
            newMessageBox.Text = txtTitle;
            newMessageBox.ShowDialog();
            return Button_id;
        }

using MCI time macros in C# VS2008

Sat, 28 Nov 2009 22:40:57 Z

I am working on building a media player and I need to update a label which shows the current track position. I am using the following command to retrieve the position:

mciSendString("status MediaFile length", media_length, 256, IntPtr.Zero); // where MediaFile is the alias I have used for mpegvideo device

I am using the following command to retrieve the hour component:

int hour = MCI_HMS_HOUR(trackLength);

The error I get is MCI_HMS_HOUR is not in the current context.

Thank you.

Sagar Hatekar

show the control as it is being dragged and dropped

Sun, 29 Nov 2009 01:24:40 Z

Is it possible to show the control as it is being dragged and dropped?
What I have now is a bare bones drag and drop that redraws the control around the final mouse position.
I tried to change the location property of the control, and that does work, but removes the drag and drop functionality, and cannot cross containers. Is there a solution to show the control as it is being moved?
Thanks.

how to run a X64 bit application from X86 excutable on a X64 machine.

Sat, 28 Nov 2009 11:18:54 Z

Hi,

I am trying to run qwinsta.exe from a X86 Visual Studio project, but every time I search for C:\Windows\System32\qwinsta.exe, app was throwing an exception FileNotFound. I know that the file was searched in C:\Windows\SysWOW64 from a X86 project or 32 bit application.
And more over i didnt find 32 bit version of qwinsta in SysWOW64 folder.

Could somebody help me how could I access the files from System32 folder on X64 machine from a X86 project.

Any Project settings that I could change to access these.

The main constraint is I cant build my project with Options set to "Any CPU" or "X64". I could only build set to "X86".

Thanks in advance for help.

-Regards,
Sri.

Thanks, Sri

ZedGraph

Sat, 28 Nov 2009 22:18:19 Z

I just spent a couple of hours trying to implement ZedGraph. I downloaded the dlls from SourceForge website:

http://sourceforge.net/projects/zedgraph/files/

and dropped them into VS2008 ToolBox. I followed all instructions, opened up a new project and dropped the control on one of my Tabpages. The look is very good. What I don't understand is this. I am trying to use the tutorial, A Flexible Charting Library in .NET:

http://www.codeproject.com/KB/graphics/zedgraph.aspx

and follow code samples which are also all over the web. it seems to me this latest version of the dlls is different from the one code samples relate to. I cannot invoke some classes and some methods are absent in the classes that are available. It also appears that come NameSpaces are rearranged. Before I spent another two hours I want to ask the public if anyone has had recent experience with the control. Am I doing something wrong?

For instance this code sample:

private void CreateGraph( ZedGraphControl zgc )
{
   // get a reference to the GraphPane
   GraphPane myPane = zgc.GraphPane;

gives me compilation errors. ZedGraphControl is not available as an object. I can get the Panel differently but I don't know how to connect it to the page or the graph.

This is how it works for me:

        private void CreateGraph ( ZedGraph zgc )
        {
            // get a reference to the GraphPane
            ZedGraph.GraphPane myPane = new ZedGraph.GraphPane ( );
            // Set the Titles
            myPane.Title.Text = "My Test Graph\n(For CodeProject Sample)";
            myPane.XAxis.Title.Text = "My X Axis";
            myPane.YAxis.Title.Text = "My Y Axis";

Thanks.

AlexB

How to get aero working with winforms usercontrolls?

Sat, 28 Nov 2009 22:24:55 Z

I have managed to get my form to use aero but I haven't realy found a way to apply aero to my controls, the only information I found was on a codeproject article, and that was using unmanaged c++

i don't know where to put this question but pleese answer me ,can we adjust swf file that doesnot have source code????

Sat, 28 Nov 2009 20:58:57 Z

hiii alll
i hope you to answer me ..

i have swf file but without source code and i want to hide some writings over it

do any one have any any idea
???

can we change the type if swf file to vedio so we can adjust it in some way ?????????????????????????

Is it better to var than an explicit type?

Sat, 28 Nov 2009 21:23:58 Z

In a function like:
string test = "Hello World"

string can be replaced by var. This has been advocated as a useful refactor in some quarters --- why?

Folder lock in C#

Sun, 22 Nov 2009 00:55:32 Z

I wanted to create folder lock to apply on some of my folders(to hide their contents) in such a way that I can lock and open them with a password. I read several articles about folder-lock but had hard time to understand. Is there anybody that can give me a simple code which can help me to uderstand this issue .... I am using C# 2008 express edition.

thanks.

Parsing Date to String in query

Fri, 27 Nov 2009 20:09:32 Z

Hi!
Im trying to select from table Date.
I have method DoScalarString.

But if I write:
string CourseStartDate = DBOperations.DoScalarString("SELECT StartDate FROM Courses WHERE Title = '"+txt_course_client.Text+"'");

I get can't cast DateTime to String

If I try ("Select VALUE CAST (StartDate AS string) FROM....."),

I get "IErrorInfo.GetDescription failed with E_Fail(0X.....)"

If I do this:

DateTime

CourseStartDate = DBOperations.DoScalarDateTime("SELECT StartDate FROM Courses WHERE Title = '"+txt_course_client.Text+"'");

Folowinf works, but I it needs a whole method additionally. Is there a way to make it like I tried with CAST? Where is there bug?

Thanks!

? Operator

Sat, 28 Nov 2009 20:51:42 Z

Can someone explain the following statement to me?

5 == 1 ? 5

Bulk Insert problem

Fri, 27 Nov 2009 01:03:00 Z

Hello All

I have been trying to enter multiple records in database . Until now I was trying one by one insertion but I dont think its most efficient way .
What I am doing is : getting all drivers from c:\windows\system32\drivers folder using WMI query.
Here is the code that I am using :

                //Open WMI connection to get Drive info

                //Build an options object for the connection

                ConnectionOptions options = new ConnectionOptions();

                options.Impersonation = ImpersonationLevel.Impersonate;



                //Make a connection to a remote computer using these options



                ManagementScope scope = new ManagementScope("\\\\" + serverName + "\\root\\cimv2", options);



                ObjectQuery driverQuery = new ObjectQuery("Select * from Win32_SystemDriver where Started='true'");//





                ManagementObjectSearcher searcher = new ManagementObjectSearcher(scope, driverQuery);



                ManagementObjectCollection oReturnCollection = searcher.Get();

                int count = oReturnCollection.Count;

                SqlDataAdapter adapter=new SqlDataAdapter();

                foreach (ManagementObject driverVar in oReturnCollection)

                {

                    int driverID = 0;

                    try

                    {

                        collectorConn.Open();

                        

                        ["PathName"].ToString();





                        sDriverName = driverVar["name"].ToString();

                        sErrorControl = driverVar["ErrorControl"].ToString();

                        sStatus = driverVar["status"].ToString();

                        sStarted = driverVar["started"].ToString();

                        sPathName = driverVar["PathName"].ToString();



                        char[] sep = { '\\' };

                        string[] splitPath = sPathName.Split(sep);

                        int totalSplits = splitPath.Count();



                     



                        FileVersionInfo fvInfo = null;

                        try

                        {

                            //fvInfo = FileVersionInfo.GetVersionInfo(sPathName);

                            fvInfo = FileVersionInfo.GetVersionInfo("\\\\" + serverName + "\\C$\\WINDOWS\\system32\\drivers\\" + splitPath[totalSplits-1].ToString());

                            sDriverVersion = fvInfo.FileVersion.ToString();

                           

                        

                        }

                        catch

                        {

                            sDriverVersion = "";

                        }

                        





                        SqlCommand addCmd = new SqlCommand();

                        addCmd.CommandText = "aut_AddServerDriver";

                        addCmd.CommandType = CommandType.StoredProcedure;

                        addCmd.Connection = collectorConn;



                        SqlParameter srvidParm = new SqlParameter("@ServerID", SqlDbType.Int);

                        srvidParm.Direction = ParameterDirection.Input;

                        srvidParm.Value = serverID;

                        addCmd.Parameters.Add(srvidParm);



                        SqlParameter nameParm = new SqlParameter("@DriverName", SqlDbType.VarChar);

                        nameParm.Direction = ParameterDirection.Input;

                        nameParm.Value = checkNull(sDriverName);

                        addCmd.Parameters.Add(nameParm);



                        SqlParameter pathParm = new SqlParameter("@Path", SqlDbType.VarChar);

                        pathParm.Direction = ParameterDirection.Input;

                        pathParm.Value = checkNull(sPathName);

                        addCmd.Parameters.Add(pathParm);



                        SqlParameter errorParm = new SqlParameter("@ErrorControl", SqlDbType.VarChar);

                        errorParm.Direction = ParameterDirection.Input;

                        errorParm.Value = checkNull(sErrorControl);

                        addCmd.Parameters.Add(errorParm);



                        SqlParameter statusParm = new SqlParameter("@Status", SqlDbType.VarChar);

                        statusParm.Direction = ParameterDirection.Input;

                        statusParm.Value = checkNull(sStatus);

                        addCmd.Parameters.Add(statusParm);



                        SqlParameter versionParm = new SqlParameter("@Version", SqlDbType.VarChar);

                        versionParm.Direction = ParameterDirection.Input;

                        versionParm.Value = checkNull(sDriverVersion);

                        addCmd.Parameters.Add(versionParm);



                        SqlParameter startedParm = new SqlParameter("@Started", SqlDbType.VarChar);

                        startedParm.Direction = ParameterDirection.Input;

                        startedParm.Value = checkNull(sStarted);

                        addCmd.Parameters.Add(startedParm);



                        SqlParameter idParm = new SqlParameter("@DriverID", SqlDbType.Int);

                        idParm.Direction = ParameterDirection.Output;

                        addCmd.Parameters.Add(idParm);



                        addCmd.ExecuteNonQuery();

                        driverID = Convert.ToInt32(addCmd.Parameters["@DriverID"].Value);

here I am making entry of each driver one by one in database. I was thinking of creating a datatable and making bulkentry of that . Is it good solution. I dont see any improvement.
Here is the changes :

                //Open WMI connection to get Drive info

                //Build an options object for the connection

                ConnectionOptions options = new ConnectionOptions();

                options.Impersonation = ImpersonationLevel.Impersonate;



                //Make a connection to a remote computer using these options



                ManagementScope scope = new ManagementScope("\\\\" + serverName + "\\root\\cimv2", options);



                ObjectQuery driverQuery = new ObjectQuery("Select * from Win32_SystemDriver where Started='true'");//





                ManagementObjectSearcher searcher = new ManagementObjectSearcher(scope, driverQuery);



                ManagementObjectCollection oReturnCollection = searcher.Get();

                int count = oReturnCollection.Count;

                DataTable dt = CreateTable();

                SqlDataAdapter adapter=new SqlDataAdapter();

                foreach (ManagementObject driverVar in oReturnCollection)

                {

                    DataRow dr = dt.NewRow();

                   

                    int driverID = 0;

                    try

                    {

                        collectorConn.Open();

                        

                        dr["serverId"] = serverID;

                        dr["driverName"]=driverVar["name"].ToString();

                        dr["pathName"] = driverVar["PathName"].ToString();

                       

                               

                                sPathName = driverVar["PathName"].ToString();



                        char[] sep = { '\\' };

                        string[] splitPath = sPathName.Split(sep);

                        int totalSplits = splitPath.Count();



                        dr["ErrorControl"] = driverVar["ErrorControl"].ToString();

                        dr["status"] = driverVar["status"].ToString();

                       

                        dr["started"] = driverVar["started"].ToString();



                        FileVersionInfo fvInfo = null;

                        try

                        {

                            //fvInfo = FileVersionInfo.GetVersionInfo(sPathName);

                            fvInfo = FileVersionInfo.GetVersionInfo("\\\\" + serverName + "\\C$\\WINDOWS\\system32\\drivers\\" + splitPath[totalSplits-1].ToString());

                            sDriverVersion = fvInfo.FileVersion.ToString();

                           

                        

                        }

                        catch

                        {

                            sDriverVersion = "";

                        }

                        dr["driverVersion"] = sDriverVersion;

                        dt.Rows.Add(dr);



                   

                }

        

                using (SqlBulkCopy copy = new SqlBulkCopy(collectorConn))

                {



                    copy.DestinationTableName = "ServerDriver";

                    copy.WriteToServer(dt);

                }

                collectorConn.Close();

Is there any better solution of inserting around 100 records in database using bulcopy or something?

Many thanks for any suggestion!!

What data method to use when returning multiple rows, assigning to a dataset?

Fri, 27 Nov 2009 22:11:20 Z

I know to retreive one value, you use ExecuteScalar, and to perform an action (such as Update or Insert), you use ExecuteNonQuery. What, though, for a Select statement returning (potentially) multiple rows. For example, assigning the result set to a Dataset?

Writer / Photographer: www.lulu.com/blackbirdcraven, www.bclayshannon.photoshop.com

Reflection

Sat, 28 Nov 2009 18:13:32 Z

How can I use System.Reflection to see what exactly is going on in a class?

NetworkStream.Read() is too slow, pauses after each read

Fri, 27 Nov 2009 23:12:37 Z

I'm trying to receive a file that's about 500KB - more than NetworkStream.Read() can read in one go so I'm looping it, but file transfers take ages... I have a label/progressbar that shows the transfer and I can see it transfers a chunk or so fast, then just stops, waits, then transfers another chunk. I have no idea why it's doing this but it's slowing it down ridiculously.

Here's my code:

packet = new byte[Client.CData[id].dirSize];
                            while (bytesRead < Client.CData[id].dirSize)
                            {
                                bytesRead += clientStream.Read(packet, bytesRead, Client.CData[id].dirSize - bytesRead);
                                if (Client.CData[id].fFileManager != null)
                                {
                                    Client.CData[id].fFileManager.progressStatus.Text = "Received " + bytesRead.ToString() + " of " + Client.CData[id].dirSize.ToString() + " bytes.";
                                    int percentage = (bytesRead * 100 / Client.CData[id].dirSize);
                                    Client.CData[id].fFileManager.progressBar.Value = percentage;
                                }
                            }

CData[id].dirSize is the size of the file overall.

What am I doing wrong?

TFTP

Thu, 26 Nov 2009 19:55:28 Z

I need to transfer data from a laptop to target device via TFTP.

I can instruct the target device to begin waiting for my data and now need to just begin sending the data from my side.

However, I don't see what class is available in C# for me to implement my side of the TFTP transfer.

Is there such a class in C#?

Thanks

-Mike

BackgroundWorker

Tue, 24 Nov 2009 21:09:56 Z

Hi.
I have a class with a method named Import() { ... }. This methos is a long time process (reading a database, finding envelopes of some columns and some other computing). In the application main form, I call this method and pass some parameters to it from a void function.
It works perfectly, but when I use the backgroundworker, this error occured:

Current thread must be set to single thread apartment (STA) mode before OLE calls can be made. Ensure that your Main function has STAThreadAttribute marked on it. This exception is only raised if a debugger is attached to the process.

Please help me.

Delegates and References to classes

Sat, 28 Nov 2009 18:39:12 Z

Hi

If I have the following code:

class
 A
{    

     public
 A(Action<int
> myDelegate)
     {
         MyDelegate = myDelegate;
     }
 
    Action<int
> MyDelegate {get
; private
 set
;}
}


class
 B
{   

  public
 B(Action<int
> myDelegate)
     {
         MyDelegate = myDelegate;
     }
 
    Action<int
> MyDelegate {get
; private
 set
;}
}

If I do:

 Action<int
> action = i => DoSomething(i);

 A = new

 A(action);
 B = new

 B(A.MyDelegate);

Will the class B be created with the reference to the underlying delegate or will it keep a reference to class A? As if it keeps a reference to class A and I want class A to be garbage collected it could create a memory leak as long as B is alive.

Thank you

Base64 and Byte Conversion

Sat, 28 Nov 2009 02:11:44 Z

Hello,

I have the following:
String result = Convert.ToBase64String(Encoding.UTF8.GetBytes("Test"));

Shouldn't result become "Test"? I get "VGVzdA=="

I am using this approach to save Byte data into a XML file and get it back to a string.
It isn't working so I made this test and I was expecting to get "Test" in result.

Thanks,
Miguel

How to i Converty Object to Image?

Sat, 28 Nov 2009 17:19:13 Z

hi Friend,

I need to convert an Object to Image type, but in which namespace / reference type "Image" resides?

thanks

Late-Binding problem

Sat, 28 Nov 2009 15:51:07 Z

I'm trying to convert the following VB.Net code to C#

Dim DB As DAO.Database = New DAO.DBEngine().OpenDatabase("C:\Northwind.mdb")
        Dim td As DAO.TableDef = DB.TableDefs("Customers")
        For Each idx As DAO.Index In td.Indexes
            If idx.Primary Then
                For i As Int32 = 0 To idx.Fields.Count - 1
                    MsgBox(idx.Fields(i).Name)
                Next
            End If
        Next

The problem is in the line
.......For i As Int32 = 0 To idx.Fields.Count - 1
The property "Count" doesn't show up in Intellisense (neither in VB.Net or C#). In fact you can't even write, in C#,
......MsgBox(idx.Fields(i).Name)
because "Fields" shows up as a single object, not as an array or collection of fields. Yet in VB.Net I can get away with all this, apparently because it does late-binding automatically. In C# I tried the following (to at least access the "Count" value even though this still falls short of accessing the "Name" value):

DAO.TableDef TD = CurrentDB.TableDefs[oTab.Table];
            foreach (DAO.Index idx in TD.Indexes)
                if (idx.Primary)
                {
                    Type oType = idx.Fields.GetType();
                    System.Reflection.PropertyInfo pi = oType.GetProperty("Count");
                    int Count = (int)pi.GetValue(idx.Fields, null);
                }

But "pi" comes out "null". So I can't even get the Count value, much less the Name values (which is what I really need). Any ideas? (If you want to try this yourself, please add a reference to Microsoft DAO 3.6 Object Library). Thanks for any help !

How to convert an object to byte[ ]?

Sat, 28 Nov 2009 15:50:37 Z

Hi Friend,

I dont think i;ve written the thread in an understandable way....actually i need to convert a value in a datarow cell that of type varbinary(in DB) to byte[]?

thanks

C#

Sat, 28 Nov 2009 16:07:44 Z

how we can write a program for drawing pyramid using for loop in c sharp?

From picturebox to database

Sat, 28 Nov 2009 01:17:53 Z

How to put image from picturebox to database using Linq???

Thanks

A socket is disposed of in a Timeout and I get an error in ReceiveCallBack() trying to access..

Mon, 23 Nov 2009 21:55:26 Z

Hightlighted in large purple font below are the two lines where the following errors occur and this order;
1. int bytesRead = client.EndReceive(ar); in ReceiveCallBack() and
2. client.Shutdown(SocketShutdown.Both); in DeviceCommunicationTimeOut

I can see that the TimeOut, after 125 milliseconds, is closing the socket and then when there is an unsuccessful attempt to access the socket in the ReceiveCallBack(). But I haven't figured out how to prevent that. Thank you so much for any help on my first asynchronous socket app.

public class StateObject

    {

        public Socket workSocket = null;

        public const int BufferSizeForReceive = 2400;

        public byte[] buffer = new byte[BufferSizeForReceive];

        public StringBuilder sb = new StringBuilder();

        private static byte[] toSocket;

    }

    public partial class Form1 : Form

    {

        private static System.Threading.Timer timerForTimeOut = null;  //one shot 

        private static Object syncObj = new Object();  //Lock when receiving data or TimeOut called



        private static ManualResetEvent connectDone = new ManualResetEvent(false); //??

        private static ManualResetEvent receiveDone = new ManualResetEvent(false); //??

        private static ManualResetEvent sendDone = new ManualResetEvent(false);    //??



        private static byte[] toSocket;

        private static string response;

        private static string softwareVersionFromDevice;

        private static string host = "10.0.110.35";

        private static Int32 port = 50000;

        public Form1()

        {

            InitializeComponent();

            toSocket = new byte[7];

            toSocket[0] = 2; //msgID

            toSocket[1] = 0; //status

            toSocket[2] = 0; //data lehgth

            toSocket[3] = 0;

            toSocket[4] = 0; //seq #

            toSocket[5] = 1;

        }



        private void button1_Click(object sender, EventArgs e)

        {

            BeginConnect(host, port);

        }

        public static void BeginConnect(string host, int port)

        {

            try

            {

                Socket s = new Socket(AddressFamily.InterNetwork,

                    SocketType.Stream,

                    ProtocolType.Tcp);

                connectDone.Reset();

                s.BeginConnect(host, port, new AsyncCallback(ConnectCallback), s);

                connectDone.WaitOne();

            }

            catch (Exception ex)

            {

                Console.Write("BeginConnect exception = " + ex.ToString());

            }

        }



        public static void ConnectCallback(IAsyncResult ar)

        {

            try

            {

                Socket client = (Socket)ar.AsyncState;

                client.EndConnect(ar);

                connectDone.Set();

                // create a one-shot timer

                if (timerForTimeOut == null)

                    timerForTimeOut = new System.Threading.Timer(DeviceCommunicationTimeOut, client, 125, 125);

                Send(client);

            }

            catch (Exception ex)

            {

                Console.Write("ConnectCallback exception = " + ex.ToString());

            }

        }

        private static void DeviceCommunicationTimeOut(object state)

        {

            try

            {

                Socket client = (Socket)state;



                lock (syncObj)

                {

                    // timed out. close and shutdown socket

                    client.Shutdown(SocketShutdown.Both); 

                    client.Close();

                }



            }

            catch (Exception ex)

            {

                Console.Write("DeviceCommunicationTimeOut exception = " + ex.ToString());

            }

        }



        private static void Send(Socket client)

        {

            try

            {

                client.BeginSend(toSocket, 0, toSocket.Length, SocketFlags.None,

                new AsyncCallback(SendCallback), client);

            }

            catch (Exception ex)

            {

                Console.Write("Send exception = " + ex.ToString());

            }

        }



        private static void SendCallback(IAsyncResult ar)

        {

            Socket client = (Socket)ar.AsyncState;

            int bytesSent = client.EndSend(ar);

            sendDone.Set();

            Receive(client);

        }



        private static void Receive(Socket client)

        {

            try

            {

                StateObject state = new StateObject();

                state.workSocket = client;

                client.BeginReceive(state.buffer, 0, StateObject.BufferSizeForReceive, 0,

                new AsyncCallback(ReceiveCallback), state);

            }

            catch (Exception ex)

            {

                Console.Write("Receive exception = " + ex.ToString());

            }

        }



        private static void ReceiveCallback(IAsyncResult ar)

        {

           try

           {

              lock (syncObj)

              {

                 timerForTimeOut.Change(125, 10000);    // Timeout.Infinite

              }

              StateObject state = (StateObject)ar.AsyncState;

              Socket client = state.workSocket;

              int     bytesRead = client.EndReceive(ar); 

              if (bytesRead > 0)

              {

                    state.sb.Append(Encoding.ASCII.GetString(state.buffer, 0, bytesRead));

                    client.BeginReceive(state.buffer, 0, StateObject.BufferSizeForReceive, 0,

                    new AsyncCallback(ReceiveCallback), state);

              }

              else

              {

                 if (state.sb.Length > 1)

                 {

                    response = state.sb.ToString();

                 }

                 receiveDone.Set();

              }

           }

           catch (ObjectDisposedException ex)

           {

              Console.WriteLine("EndReceive exception = " + ex.ToString());

           }

  

        }

    }

Changing an inherited properties Attribute value

Thu, 26 Nov 2009 03:06:18 Z

Greetings,

I currently have a class that inherits from a base class. The base class has a property called Name with a DefaultValueAttribute attached to it. I need to be able to change the DefaultValueAttribute on my child class, without re-declaring the property. Something to this affect...

Psuedo code:

class Character
{
    [DefaultValueAttribute("New Character")]
    string name
}

class NPC
{
    NPC()
    {
        //Change DefaultValueAttribute here to New NPC instead of New Character
    }
}

Thanks for any tips

Free iPhone ringtone conversion utility. (iringtones.codeplex.com) Follow me on Twitter: Scionwest follow my blog: Scionwest.blogspot.com Developing a managed scripting engine (ManagedScripting.com)

color change in rich text box

Fri, 27 Nov 2009 16:07:44 Z

i want to change the color of the text written in rich text box ......i tried this but it does not work
pls help
code snippet is given below:

Color cc = Color.FromArgb(255, 5, 5);
richTextBox1.SelectionColor = cc;

How to check and correct text in dataViewGrid cells

Thu, 26 Nov 2009 19:51:26 Z

Hello. I have a problem.
I want to check what user writes into first column cells. I want to check it in CellLeave event

i've write some code but it doesn't do what i want. When I leave cell nothing happens, i need to click on this cell again and leave it again. I'd like to make simple check. An user types into cell a file extension and if it's written without *. at he begining my code should add this signs to this extension

My code:

  private void dataGridView1_CellLeave(object sender, DataGridViewCellEventArgs e)



        {



            



             try



             {



               



               



                 string content;



                 if (System.Convert.ToString(dataGridView1[dataGridView1.CurrentCell.ColumnIndex, dataGridView1.CurrentCell.RowIndex].Value) != "")



                 {







                     content = System.Convert.ToString(dataGridView1[dataGridView1.CurrentCell.ColumnIndex, dataGridView1.CurrentCell.RowIndex].Value);



                     if (e.ColumnIndex == 0)



                     {







                             if (content[0] != '*')



                                 dataGridView1[dataGridView1.CurrentCell.ColumnIndex, dataGridView1.CurrentCell.RowIndex].Value = content.Insert(0, "*");



                             if (content[1] != '.')



                                 dataGridView1[dataGridView1.CurrentCell.ColumnIndex, dataGridView1.CurrentCell.RowIndex].Value = content.Insert(1, ".");



                      }


                 }



             }



             catch (Exception ex)



             {



                 MessageBox.Show(ex.Message);



             }



           
        }

Desktop shortcut

Fri, 27 Nov 2009 22:07:33 Z

How to create a shortcut on the user`s desktop, while application is being installed?

What do I need to do in the Setup Project?

This is what I did, but there is no Icon on the desktop:

Install custom font/cursors with the application...

Sat, 28 Nov 2009 12:31:26 Z

hi...

In my application i need some custom fonts & cursors to be used. How i can check if the corrosponding font is installed or not...?
If the font is not installed then how to install the font and cursor.
Is there any sample document/code to explain this...?
I am using VS2005 .Net2.0.

Thanks in advance,
IamHuM