C# Textbox - enter only positive numbers on KeyPress event in Windows form application

To prevent users from entering incorrect data in Windows form application, set restriction to allow only specific characters to be entered in the text box.This example uses KeyPress event to monitor the users input and to apply the restriction required.To avoid code duplication in Windows multiform applications for example, a separate class file is created “CommonFunctions.cs”.
The function to allow only numbers in textbox control is named InputNumbers.
For each Windows form, create a single KeyPress event and call the InputNumbers function inside it.
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2017/10/05 02:27

C# How to draw shapes – Circle, Rectangle, Arc, Pie, Polygon, Bezier, Text

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In order to draw shapes in C# a start point and end point coordinates, and a Pen control must be defined first.
Coordinates in C#The value of x is the location of the point along the x-axis, the 0 is at the extreme left. The value of y is the location of the point along the y-axis, the 0 is at the extreme top.
2017/10/05 01:56

C# Custom control – TextBox accepting only numbers, decimal numbers, signed numbers

The creation of custom control using Visual Studio involves the following steps:
  1. Start Visual Studio;
  2. Create new “Windows Control Library” project;
  3. In the created project delete “User Control” file;
  4. Go to “Project” > “Add User Control” and give it a name;
  5. Change the inherited class to this that you want your control to be;
  6. Create you custom properties for the control;
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    2017/10/05 00:51

Handling CheckedListBox ItemCheck event in C#

Common problem handling ItemCheck event in CheckedListBox control is the fact that when the event is fired the object's state change is not finalized.If within the ItemCheck event handling function we try to get the CheckedListBox item's check state using the most common methods like getting collection of all checked items
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2015/11/19 10:16

C# How to Modify DataSet Connection Strings at Runtime?

Detailed instructions by Paul Keister in his excellent article Adaptive Connection Strings for Windows Forms Applications
In brief
the connection string property is set read only in the Settings.Designer.cs class:
public string MyAppConnectionString {
   get {
            return ((string)(this["MyAppConnectionString"]));
         }
}

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2015/10/19 11:07

Create application log file in C# / Write to File example

Application log file example
private string logFile = "full path and file name (C:\\temp\\MyApplicationLog.txt)";
...
WriteToLogFile("your application message", logFile); // use any time to add record to the log file
...
public void WriteToLogFile(string strMessage, string outputFile)
{
   string line = DateTime.Now.ToString() + " | ";
   line += strMessage;
   FileStream fs = new FileStream(outputFile, FileMode.Append, FileAccess.Write, FileShare.None);
   StreamWriter swFromFileStream = new StreamWriter(fs);
   swFromFileStream.WriteLine(line);
   swFromFileStream.Flush();
   swFromFileStream.Close();
}


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2014/10/19 08:55

C# Is the Logged User a member of specific Windows Domain Group?

C sharp code
using System.DirectoryServices.AccountManagement;
string userName = SystemInformation.UserName;
string UDN = SystemInformation.UserDomainName;
string domainUser = UDN + "\\" + userName;
PrincipalContext pc = new PrincipalContext(ContextType.Domain);
UserPrincipal user = UserPrincipal.FindByIdentity(pc, IdentityType.SamAccountName, domainUser);
GroupPrincipal group = GroupPrincipal.FindByIdentity(pc, "Domain_Group_Name");
bool is_member = user.IsMemberOf(group);

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2013/10/19 11:10

DataGridView add row - C#

Considering DataGridView with 3 text columns defined.
string[] row = new string[] { "column1_content", "column2_content", "column3_content" };
DataGridView1.Rows.Add(row);



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2012/10/19 09:18

DataGridView copy to clipboard

To copy the content of DataGridView cells to clipboard using MouseClick function                                                       
private void DataGridView1_MouseClick(object sender, MouseEventArgs e)
{
   DataGridView1.ClipboardCopyMode = DataGridViewClipboardCopyMode.EnableWithoutHeaderText;
   DataGridView1.SelectAll();
   Clipboard.SetDataObject(DataGridView1.GetClipboardContent());
}


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2012/10/19 09:15