docs-desktop/dotnet-desktop-guide/framework/winforms/controls/how-to-respond-to-windows-forms-checkbox-clicks.md

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title	description	ms.date	dev_langs	helpviewer_keywords	ms.assetid
Respond to CheckBox Clicks	Learn how to program your Windows Forms application to perform some action depending upon the state of the check box.	03/30/2017	csharp vb cpp	Click event [Windows Forms], CheckBox control CheckBox control [Windows Forms], Click events events [Windows Forms], Click events double-clicks check boxes [Windows Forms], responding to events	c39f901e-8899-43b6-aa31-939cbf7089fb

How to: Respond to Windows Forms CheckBox Clicks

Whenever a user clicks a Windows Forms xref:System.Windows.Forms.CheckBox control, the xref:System.Windows.Forms.Control.Click event occurs. You can program your application to perform some action depending upon the state of the check box.

To respond to CheckBox clicks

1. In the xref:System.Windows.Forms.Control.Click event handler, use the xref:System.Windows.Forms.CheckBox.Checked%2A property to determine the control's state, and perform any necessary action.

   Private Sub CheckBox1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles CheckBox1.Click  
      ' The CheckBox control's Text property is changed each time the
      ' control is clicked, indicating a checked or unchecked state.  
      If CheckBox1.Checked = True Then  
         CheckBox1.Text = "Checked"  
      Else  
         CheckBox1.Text = "Unchecked"  
      End If  
   End Sub  
   

   private void checkBox1_Click(object sender, System.EventArgs e)  
   {  
      // The CheckBox control's Text property is changed each time the
      // control is clicked, indicating a checked or unchecked state.  
      if (checkBox1.Checked)  
      {  
         checkBox1.Text = "Checked";  
      }  
      else  
      {  
         checkBox1.Text = "Unchecked";  
      }  
   }  
   

   private:  
      void checkBox1_CheckedChanged(System::Object ^ sender,  
         System::EventArgs ^ e)  
      {  
         if (checkBox1->Checked)  
         {  
            checkBox1->Text = "Checked";  
         }  
         else  
         {  
            checkBox1->Text = "Unchecked";  
         }  
      }  
   

   Note

   If the user attempts to double-click the xref:System.Windows.Forms.CheckBox control, each click will be processed separately; that is, the xref:System.Windows.Forms.CheckBox control does not support the double-click event.

   Note

   When the xref:System.Windows.Forms.CheckBox.AutoCheck%2A property is true (the default), the xref:System.Windows.Forms.CheckBox is automatically selected or cleared when it is clicked. Otherwise, you must manually set the xref:System.Windows.Forms.CheckBox.Checked%2A property when the xref:System.Windows.Forms.Control.Click event occurs.

   You can also use the xref:System.Windows.Forms.CheckBox control to determine a course of action.

To determine a course of action when a check box is clicked

1. Use a case statement to query the value of the xref:System.Windows.Forms.CheckBox.CheckState%2A property to determine a course of action. When the xref:System.Windows.Forms.CheckBox.ThreeState%2A property is set to true, the xref:System.Windows.Forms.CheckBox.CheckState%2A property may return three possible values, which represent the box being checked, the box being unchecked, or a third indeterminate state in which the box is displayed with a dimmed appearance to indicate the option is unavailable.

   Private Sub CheckBox1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles CheckBox1.Click  
      Select Case CheckBox1.CheckState  
         Case CheckState.Checked  
            ' Code for checked state.  
         Case CheckState.Unchecked  
            ' Code for unchecked state.  
         Case CheckState.Indeterminate  
            ' Code for indeterminate state.  
      End Select
   End Sub  
   

   private void checkBox1_Click(object sender, System.EventArgs e)  
   {  
      switch(checkBox1.CheckState)  
      {  
         case CheckState.Checked:  
            // Code for checked state.  
            break;  
         case CheckState.Unchecked:  
            // Code for unchecked state.  
            break;  
         case CheckState.Indeterminate:  
            // Code for indeterminate state.  
            break;  
      }  
   }  
   

   private:  
      void checkBox1_CheckedChanged(System::Object ^ sender,  
         System::EventArgs ^ e)  
      {  
         switch(checkBox1->CheckState) {  
            case CheckState::Checked:  
               // Code for checked state.  
               break;  
            case CheckState::Unchecked:  
               // Code for unchecked state.  
               break;  
            case CheckState::Indeterminate:  
               // Code for indeterminate state.  
               break;  
         }  
      }  
   

   Note

   When the xref:System.Windows.Forms.CheckBox.ThreeState%2A property is set to true, the xref:System.Windows.Forms.CheckBox.Checked%2A property returns true for both xref:System.Windows.Forms.CheckState.Checked and xref:System.Windows.Forms.CheckState.Indeterminate.

See also

• xref:System.Windows.Forms.CheckBox
• CheckBox Control Overview
• How to: Set Options with Windows Forms CheckBox Controls
• CheckBox Control