Dot Net Tips & Tricks

How to mask the Password text in Textboxes (in VB.NET / C#)

2009-06-13T19:11:00.000-07:00

It is simple to mask the characters entered in a textbox by setting the PasswordChar Property

The same can be done using C# code as shown below:

TextBox2.PasswordChar = "*"

Text Box without Mask

PasswordChar Property in TextBox

Masked Textbox

Frame Control in VB.NET / C#

2009-06-13T19:09:00.000-07:00

GroupBox control in .NET (Vb/C#)

GroupBox and Panel control provide the functionality similar to the Frame control in visual basic 6.0. Drag and Drop the Frame Control to the form and set its properties accordingly

Alter the properties from properties dialog box

How to Disable Custom Colors in ColorDialog using C# (.NET)

2009-04-21T17:32:00.000-07:00

How to restrict the user to pre-defined colors in C# ColorDialog

With .NET’s ColorDialog one can select the pre-defined as well as the custom colors. For some reason, if you want only the pre-defined colors to be selected. Set the AllowFullOpen to false.

private void btnSelectColor_Click(object sender, EventArgs e)

{

colorDialog1.AllowFullOpen = false;

colorDialog1.ShowDialog();

this.BackColor = colorDialog1.Color;

}

ColorDialog with custom colors

Restricted ColorDialog

How to use ColorDialog in C# (.NET)

2009-04-17T21:59:00.000-07:00

Allow user to customize form background color using ColorDialog

The Windows Forms ColorDialog component is a pre-configured dialog box that allows the user to select a color from a palette and to add custom colors to that palette. It is the same dialog box that you see in other Windows-based applications to select colors. Use it within your Windows-based application as a simple solution in lieu of configuring your own dialog box.

To add the dialog to Windows Form select the ColorDialog from the tool box

The component will be dropped in the component-tray below the form

Use the following code to show the dialog and set the selected color as the background of the form

private void btnSelectColor_Click(object sender, EventArgs e)

{

colorDialog1.ShowDialog();

this.BackColor = colorDialog1.Color;

}

The form will be set as shown below

Argument '1': cannot convert from 'int' to 'System.Windows.Forms.ListViewItem.ListViewSubItem'

2009-03-07T06:09:00.000-08:00

The best overloaded method match for 'System.Windows.Forms.ListViewItem.ListViewSubItemCollection.Add(System.Windows.Forms.ListViewItem.ListViewSubItem)' has some invalid arguments

ListViewItem lView = new ListViewItem() ;

lView.SubItems.Add(36);

lView.SubItems.Add("36");

How to Set the Control’s background to system colors

2009-03-07T06:08:00.000-08:00

Here is a way to use the available default system colors like control, button face etc using C#

listView1.BackColor = System.Drawing.SystemColors.ControlDark;

Cannot implicitly convert type 'int' to 'System.Collections.Generic.IEnumerable

2009-02-22T03:53:00.000-08:00

Cannot implicitly convert type 'int' to 'System.Collections.Generic.IEnumerable

public static IEnumerable<int> GetOdd()

{

// Use yield to return only the odd numbers.

foreach (int i in ints)

if (i % 2 == 1)

return i;

}

Check if you are missing any yield statement in the return

public static IEnumerable<int> GetOdd()

{

// Use yield to return only the odd numbers.

foreach (int i in ints)

if (i % 2 == 1)

yield return i;

}

How to use Background worker control in C#

2009-02-17T17:50:00.000-08:00

How to print a document in background using C#

Many time-consuming tasks can be done asynchronously. This can be done using multithreaded applications. Fortunately visual studio .net has the background worker control does all the mundane multithreading efforts by itself

Let us go back to our good old select file application (as shown below). To the form add the background worker control, which will be placed on the tray.

Once the user clicks the OK button, the background worker is called using RunWorkerAsync method. This will execute the backgroundWorker1_DoWork event while the Windows form responds to the user actions.

private void buttonOK_Click(object sender, EventArgs e)

{

if (txtExcelFile.Text.Length == 0)

{

System.Console.Beep();

MessageBox.Show ("Select the file and continue...");

}

backgroundWorker1.RunWorkerAsync(txtExcelFile.Text);

}

Status of the process is updated to the Form

private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)

{

// Replace with the actual code of printing the document

String sFile = e.Argument.ToString();

for (int i1 = 1; i1 <>

{

for (int i2 = 1; i2 <>

{

toolStripStatusLabel1.Text = "Printing " + sFile + "...";

}

You can also use the backgroundWorker1.ReportProgress method to update the status through backgroundWorker1_ProgressChanged event

private void backgroundWorker1_ProgressChanged(object sender, ProgressChangedEventArgs e)

{

toolStripStatusLabel1.Text = e.ProgressPercentage.ToString() + " percent completed";

}

The completion of the background worker can be ascertained by the RunWorkerCompleted event

private void backgroundWorker1_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)

{

toolStripStatusLabel1.Text = "Printing completed";

}

How to run a process in background using .NET, How to handle background events in .NET

How to use Treeview designer in C# Application

2009-02-17T17:43:00.000-08:00

C# Treeview designer example

Treeview control gives a nice hierarchical view for the users of a given concept. The following example shows how to create a simple tree-view control using the designer

Add a Tree View Control to the form

Select the TreeView Tasks from the control

Add the root item – XYZ Automobiles

Click the root item and then click on the Add Child to add children. Repeat the steps to add more children

The form will be displayed as shown below

The above can be done through C# code as shown below:

private void AddTreeViewControls()

{

treeView1.Nodes.Add("Root","XYZ Autombiles");

treeView1.Nodes["Root"].Nodes.Add("PV", "Passenger Vehicles");

treeView1.Nodes["Root"].Nodes.Add("CV", "Commercial Vehicles");

}

This BackgroundWorker states that it doesn't report progress. Modify WorkerReportsProgress to state that it does report progress.

2009-02-17T17:42:00.000-08:00

The error occurs when the WorkerReportsProgress of the background worker is not set.

This should be set (to True ) from the properties window

How to get the selected node in tree view from MouseDown event using C#

2009-02-17T17:32:00.000-08:00

C# - MouseDown event in Tree View Control

Here is a way to get the selected tree view node using C#. The snippet uses the X and Y co-ordinates to get the node

private void treeView1_MouseDown(object sender, MouseEventArgs e)

{

Point p1 = new Point(e.X, e.Y);

TreeNode N1 = treeView1.GetNodeAt(p1) ;

MessageBox.Show(N1.Text);

}

How to add nodes to the tree view control using C#

2009-02-17T17:29:00.000-08:00

How to build a tree view using C#

The following snippet helps to build a simple tree view.

Tree View Control

Add a Tree View Control to the form

The following code adds a simple treeview with a root node and two children

private void AddTreeViewControls()

{

treeView1.Nodes.Add("Root","XYZ Autombiles");

treeView1.Nodes["Root"].Nodes.Add("PV", "Passenger Vehicles");

treeView1.Nodes["Root"].Nodes.Add("CV", "Commercial Vehicles");

}

The nodes are added using the Add method – the first parameter is the Key and the second is the node text. The child nodes are added to the root using the Key

treeView1.Nodes["Root"]

How to sort listview items in C#

2009-02-17T17:26:00.002-08:00

Here is a simple example of sorting list view items using C#

listView1.Items.Add("Banana");

listView1.Items.Add("Apple");

listView1.Sorting = SortOrder.Ascending ;

ListView before Sorting

ListView after Sorting

How to delete all items from a ListView using C#

2009-02-17T17:26:00.001-08:00

To remove all listview items use the clear method

For example:

listView1.Clear();

will empty the listview

A simple StatusStrip Control Example using C#

2009-01-25T17:53:00.000-08:00

C# StatusBar Example

Status bars play an important part in informing the user of the use of controls, the status of progress of the application etc. .Net provides a new control – the StatusStrip control – an extension of StatusBar

Let us have a small Windows form like the one as shown below.

Select the StatusStrip control in the ToolBox and drop it on the form

When you drop the control will be placed on the Tray below the form and a StatusStrip with a ToolStripLabel will be added to the Form

Now the ToolStripLabel can be used to apprise the user of the context and progress as shown below

private void buttonSelectXL_MouseHover(object sender, EventArgs e)

{

toolStripStatusLabel1.Text = "Click the Button to select the file";

}

.NET StatusBar Example, .NET ToolStripLabel Example

How to use C# MouseOver Events in Windows Forms

2009-01-25T17:48:00.000-08:00

Yet again we take the good old select file form as our example. Let us use the MouseHover event of the ellipsis button to inform the user of its function.

To add an function to handle the event, click the event tab of the button and scroll to MouseHover event and double click it.

Add the following code to the event procedure.

private void buttonSelectXL_MouseHover(object sender, EventArgs e)

{

toolStripStatusLabel1.Text = "Click the Button to select the file";

}

The toolstrip label will be updated whenever the mouse pointer is hovered over the ellipsis button.

C# Array UBound Function

2009-01-25T17:47:00.001-08:00

How to get the Upper Bound of an Array in C#

The upper bound of the array can be retrieved using the Length property as shown below:

private void GetUbound()

{

String[] arTemp = {"First","Second"};

MessageBox.Show (arTemp.Length.ToString ());

}

OpenFileDialog in C# - How to Use OpenFileDialog in C# Windows Application

2009-01-25T17:42:00.000-08:00

Common Dialog in C# (.NET)

CommonDialog was widely used to select the files in Visual Basic 6.0. .Net provides a OpenFileDialog component, which can be used for the same.

Let us have a small Windows form where the file to process is to be selected. The form contains a CommandButton to invoke the Open File dialog box and a TextBox to display the selected file.

To use the OpenFileDialog, insert the component from Toolbox to the form

When it is droped to a form, the OpenFileDialog component appears in the tray at the bottom of the Windows Forms Designer.

Now write the following code in the Button’s Click event to display the Open file dialog box

private void buttonSelectXL_Click(object sender, EventArgs e)

{

openXLFile.Filter = "Microsoft Excel Workbooks (*.xls)*.xls";

if (openXLFile.ShowDialog() == DialogResult.OK )

{

String sFileName = openXLFile.FileName;

txtExcelFile.Text = sFileName;

}

else

{

MessageBox.Show("Please select a file");

}

The above code filers only Excel files in the Open Dialog Box

The selected file will be displayed in the Textbox

See also OpenFileDialog in Visual Basic .Net

For CommonDialog implementation in VB6.0 refer http://vbadud.blogspot.com/2007/06/visual-basic-common-dialog.html

How to Add Resources to C# Windows Application

2009-01-25T17:34:00.000-08:00

How to add images as resources to C# Windows Application

Resources can be added to the C# Project using Resource Page in the Project Designer (Project à Project Properties)

The Resources page of the Project Designer hosts an instance of the Resource Designer that stores and maintains resources in a single location (Resources.resx).

The Resource Designer is language-neutral and supports projects in all Visual Studio languages. Items that you add to the project by using the Resource Designer are placed in the Resources directory for your project. The designer information is stored in a file named Resources.resx, and code for the resource is stored in Resources.Designer.cs, Resources.Designer.vb, or Resources.Designer.jsl.

Right Click the Resources section in the solution explorer and Select Add à Existing Item and select the Image files that need to be added

The images will be added as shown below

Drag the images to the Resources page – Rename the resource names if needed

Now you can use the Resources in your Form. Select the BackGroundImage from the Form’s properties box – Click on the ellipsis next to the BackGroundImage property. This will open the Select Resource dialog Box

Select appropriate resource from the list

The same can be set through code using

this.BackgroundImage = Properties.Resources.User_Single

For linkedresources see - Create HTML Message with Embedded Images in VB.NET / Embed images in HTML mail message using VB.NET

Cannot find wrapper assembly for type library "Microsoft.Office.Core".

2009-01-25T17:32:00.000-08:00

Cannot find wrapper assembly for type library "Microsoft.Office.Core".

There are updated custom wrappers available for the following referenced components: Office.

2009-01-25T17:30:00.000-08:00

There are updated custom wrappers available for the following referenced components: Office.

The referenced component 'Microsoft.Office.Core' could not be found.

2009-01-25T17:24:00.000-08:00

The referenced component 'Excel' could not be found.

The warning occurs when you open the C#/ VB.Net Solution referring a different version of Microsoft Excel / Office. For example, If you open the Project, which refers Excel 2003 (Excel 11.0 Library) in Excel 2007 machine

How to remove the Word from memory using C#

2009-01-25T17:22:00.000-08:00

How to delete the leftover Word object using C#.

Closing Word Runtimes not removed by Word.Quit / Application.Quit

When Word crashes, it often takes with it the open documents. These documents will be write-locked and will appear as read-only to subsequent users. There are umpteen no. of reasons to crash a Word document and leave the ‘Winword.exe’ running in the memory. The following VB.NET code will remove the unused Word objects from memory.

Public Sub KillUnusedWordProcess()

Dim oXlProcess As Process() = Process.GetProcessesByName("Winword")

For Each oXLP As Process In oXlProcess

If Len(oXLP.MainWindowTitle) = 0 Then

oXLP.Kill()

End If

End Sub

We have not tested the code in real-time. Our assumption was that any Word instance opened by user has a Window Title and programs using Word have been terminated. Check if the code is of any use and post the updations / suggestions to our ‘dud’ buddiesJ

automation does not close Microsoft Word, Application.Quit not closing Word

Excel Runtimes not removed by Excel.Quit / Application.Quit

2009-01-25T17:15:00.000-08:00

How to delete the leftover Excel object using VB.NET / Vb.NET delete Excel from memory

Excel runtimes that remain after the program is a nemesis. Many times this might be due to the leftover Excel objects in the program that causes Excel to remain in memory even after Application.Quit. Workbooks that are modified and left open often causes this problem. We have tried out one method to get rid of the Excel in memory using Vb.NET. We assumed that the programs that used Excel has been terminated and if any Excel remains in the memory it should be of the ‘legitimate’ application that the user has opened or the left over Excel.

We checked the presence of Title for Excel Application, which was present in all cases for the open instance of Excel. Left over instances didn’t had the title. The following code ‘kills’ the instances of Excel in memory that don’t have a WindowTitle.

Public Sub KillUnusedExcelProcess()

Dim oXlProcess As Process() = Process.GetProcessesByName("Excel")

For Each oXLP As Process In oXlProcess

If Len(oXLP.MainWindowTitle) = 0 Then

oXLP.Kill()

End If

End Sub

Try if it works for you and post your suggestions or modifications

Keywords : automation does not close microsoft excel, Application.Quit not closing Excel

No overload for method 'get_Range' takes '1' arguments

2009-01-16T19:21:00.000-08:00

No overload for method 'get_Range' takes '1' arguments is error encountered by VB programmers trying to code in C#.

Excel.Workbook oWB = oXL.Workbooks.Open(sXLFileName, missing, missing, missing, missing, missing, missing, missing, missing, missing, missing, missing, missing, missing,missing );

// processing

Excel.Worksheet oWS = (Excel.Worksheet)oWB.Worksheets[1];

oWS.get_Range("A1").Value2 = "No";

This occurs when get_Range method is supplied with only one argument. Instead use any of the following:

oWS.get_Range("A1","A1").Value2 = "No";

Object missing = System.Type.Missing;

oWS.get_Range("A1",missing ).Value2 = "No";

Error Dialog