The CheckBox control is the part of windows form which is used to take input from the user. Or in other words, CheckBox control allows us to select single or multiple elements from the given list. In CheckBox, you are allowed to get or set the state of the CheckBoxes using the CheckState property of the CheckBox. In CheckBox, there are three different types of states are available:

The default value of the CheckState property is Unchecked. In Windows form, you can set this property in two different ways:

1. Design-Time: It is the simplest way to set the CheckState property of a CheckBox using the following steps:

• Step 1: Create a windows form as shown in the below image:
  Visual Studio -> File -> New -> Project -> WindowsFormApp
  
• Step 2: Drag the CheckBox control from the ToolBox and drop it on the windows form. You can place CheckBox anywhere on the windows form according to your need.
  
• Step 3: After drag and drop you will go to the properties of the CheckBox control to set the state of the CheckBox using CheckState property.
  

  Output:
  

2. Run-Time: It is a little bit trickier than the above method. In this method, you can set the CheckState property of a CheckBox programmatically using the following syntax:

public System.Windows.Forms.CheckState CheckState { get; set; }

Here, the CheckState is used to represent the CheckState enumeration values. It also throws an InvalidEnumArgumentException if the value assigned to the CheckState property does not belong to the CheckState enumeration values. Following steps are used to set the CheckState property of the CheckBox:

• Step 1: Create a checkbox using the CheckBox() constructor provided by the CheckBox class.

  // Creating checkbox
  CheckBox Mycheckbox = new CheckBox();
  

• Step 2: After creating CheckBox, set the CheckState property of the CheckBox provided by the CheckBox class.

  // Set the CheckState property of the CheckBox
  Mycheckbox1.CheckState = CheckState.Indeterminate;
  

• Step 3: And last add this checkbox control to form using Add() method.

  // Add this checkbox to form
  this.Controls.Add(Mycheckbox);
  

  Example:

  
  

  
  
  

  using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Linq; using System.Text; using System.Threading.Tasks; using System.Windows.Forms;    namespace WindowsFormsApp5 {    public partial class Form1 : Form {        public Form1()     {         InitializeComponent();     }        private void Form1_Load(object sender, EventArgs e)     {         // Creating and setting the properties of label         Label l = new Label();         l.Text = "Select Gender:";         l.Location = new Point(233, 111);            // Adding lable to form         this.Controls.Add(l);            // Creating and setting the properties of CheckBox         CheckBox Mycheckbox = new CheckBox();         Mycheckbox.Height = 50;         Mycheckbox.Width = 100;         Mycheckbox.Location = new Point(229, 136);         Mycheckbox.Text = "Male";         Mycheckbox.CheckState = CheckState.Unchecked;            // Adding checkbox to form         this.Controls.Add(Mycheckbox);            // Creating and setting the properties of CheckBox         CheckBox Mycheckbox1 = new CheckBox();         Mycheckbox1.Height = 50;         Mycheckbox1.Width = 100;         Mycheckbox1.Location = new Point(230, 174);         Mycheckbox1.Text = "Female";         Mycheckbox1.CheckState = CheckState.Indeterminate;            // Adding checkbox to form         this.Controls.Add(Mycheckbox1);     } } }

  Output:
  

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