CheckBox Control in c#

CheckBoxes allow the user to make multiple selections from a number of options. CheckBox to give the user an option, such as true/false or yes/no. You can click a check box to select it and click it again to deselect it.

 using System;  
 using System.Drawing;  
 using System.Windows.Forms;  
 namespace WindowsFormsApplication1  
 {  
   public partial class Form1 : Form  
   {  
     public Form1()  
     {  
       InitializeComponent();  
     }  
     private void button1_Click(object sender, EventArgs e)  
     {  
       string msg = "";  
       if (checkBox1.Checked == true)  
       {  
         msg = "net-informations.com";  
       }  
       if (checkBox2.Checked == true)  
       {  
         msg = msg + "  vb.net-informations.com";  
       }  
       if (checkBox3.Checked == true)  
       {  
         msg = msg + "  csharp.net-informations.com";  
       }  
       if (msg.Length > 0)  
       {  
         MessageBox.Show (msg + " selected ");  
       }  
       else  
       {  
         MessageBox.Show ("No checkbox selected");  
       }  
       checkBox1.ThreeState = true;  
     }  
   }  
 }