Kontrollkästchen in C#

CheckBox ist ein Steuerelement, das es dem Benutzer ermöglicht, eine oder mehrere Optionen aus einer Liste von Optionen auszuwählen. In C# wird die CheckBox-Klasse aus dem System.Windows.Forms-Namespace verwendet, um mit der Checkbox-Steuerung zu arbeiten. Es ist Teil von Windows Forms und wird verwendet, um Eingaben vom Benutzer entgegenzunehmen. Es kann auch verwendet werden, um zwischen Optionen wie wahr/falsch oder ja/nein auszuwählen.

Ein Benutzer kann auf ein Kontrollkästchen klicken, um das zugehörige Element auszuwählen, und kann erneut darauf klicken, um die Auswahl des Elements aufzuheben. Es kann zusammen mit einem Bild oder Text oder beidem verwendet werden.

Arten von Kontrollkästchen

Wir können ein Kontrollkästchen auf zwei verschiedene Arten erstellen:

1. Form Designer zur Entwurfszeit verwenden.
2. Verwenden der CheckBox-Klasse im Code zur Laufzeit.

Wir können eine CheckBox zur Entwurfszeit erstellen, indem wir ein Checkbox-Steuerelement aus der ToolBox ziehen und es dann im Windows-Formular ablegen. Dann können wir zu den Eigenschaften des Kontrollkästchen-Steuerelements gehen und es ändern.

Um zur Laufzeit ein Kontrollkästchen zu erstellen, müssen wir die CheckBox-Klasse verwenden.

Syntax: 

CheckBox check_box = new CheckBox();

Danach können wir die Eigenschaften des Kontrollkästchens entsprechend unseren Anforderungen festlegen.

//setting location of checkbox
check_box.Location = new Point(300,150);
//setting height and width for checkbox
check_box.Height = 50;
check_box.Width = 50;
//setting text for checkbox
check_box.Text = “Yes”;

Zuletzt müssen wir dieses Kontrollkästchen zum Windows Form hinzufügen, indem wir Folgendes verwenden:

this.Controls.Add(check_box);

CheckBox-Eigenschaften

C# stellt viele Eigenschaften für das Kontrollkästchen bereit.

Property	Description
AllowDrop	It is used to get or set a value that determines whether the checkbox control can accept data that a user drags onto it.
Appearance	It is used to get or set a value that determines the appearance of the checkbox control.
AutoCheck	It is used to get or set a value that determines whether the values of the Checked or CheckState properties or the appearance of the checkbox are automatically changed when the checkbox is clicked.
AutoSize	It is used to get or set a value that determines whether the checkbox control resizes based on its content.
BackColor	It is used to get or set the background color of the checkbox control.
BackGroundImage	It is used to get or set the background image displayed in the checkbox control.
CanFocus	It is used to get a value that determines whether the checkbox control can receive focus.
Checked	It is used to get or set a value that determines whether the checkbox control is in the checked state.
CheckState	It is used to get or set the state of the checkbox.
DefaultSize	It is used to get the default size of the checkbox control.
Enabled	It is used to get or set a value that determines whether the checkbox control can respond to user interaction.
Focused	It is used to get a value that determines whether the checkbox control has input focus.
Font	It is used to get or set the font of text displayed by the checkbox control.
ForeColor	It is used to get or set the foreground color of the checkbox control.
Height	It is used to get or set the height of the checkbox control.
Image	It is used to get or set the image which is displayed on the checkbox control.
Location	It is used to get or set the coordinates of the upper left corner of the control relative to the upper left corner of its parent container.
Margin	It is used to get or set the space between controls.
Name	It is used to get or set the name of the checkbox control.
Size	It is used to get or set the height and width of the checkbox control.
Text	It is used to get or set the text associated with the checkbox control.
ThreeState	It is used to get or set a value that determines whether the checkbox will allow three check states instead of two.
Width	It is used to get or set the width of the checkbox control.

CheckBox Events

Let us see some important events for the CheckBox provided by C#:

Event	Description
CheckedChanged	This event occurs when the value of Checked property changes.
CheckStateChanged	This event occurs when the value of CheckState property changes.
Click	This event occurs when the checkbox is clicked.
GotFocus	This event occurs when the checkbox receives focus.
Leave	This event occurs when the input focus leaves the checkbox.
LostFocus	This event occurs when the checkbox loses focus.
MouseClick	This event occurs when the checkbox is clicked by the mouse.
MouseDoubleClick	This event occurs when the checkbox is double-clicked by a mouse.
TextChanged	This event occurs when the value of Text property changes.

Implementation of CheckBox in C#

Below is an example of how to implement the checkbox in c #

Example:

Code:

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 WindowsFormsApp1
{
public partial class CheckBoxDemo : Form
{
public CheckBoxDemo()
{
InitializeComponent();
}
private void CheckBoxDemo_Load(object sender, EventArgs e)
{
//Creating and setting properties of Label
Label label = new Label();
label.Text = "Select your technical skills";
label.AutoSize = true;
label.Location = new Point(192, 77);
label.Font = new Font("Microsoft Sans Serif", 11);
//Adding label to form
this.Controls.Add(label);
//Creating and setting properties of CheckBox
CheckBox checkbox1 = new CheckBox();
checkbox1.Location = new Point(195, 111);
checkbox1.Text = "C";
//Adding checkbox to form
this.Controls.Add(checkbox1);
CheckBox checkbox2 = new CheckBox();
checkbox2.Location = new Point(195, 156);
checkbox2.Text = "C++";
this.Controls.Add(checkbox2);
CheckBox checkbox3 = new CheckBox();
checkbox3.Location = new Point(195, 195);
checkbox3.Text = "C#";
this.Controls.Add(checkbox3);
CheckBox checkbox4 = new CheckBox();
checkbox4.Location = new Point(195, 235);
checkbox4.Text = "JAVA";
this.Controls.Add(checkbox4);
CheckBox checkbox5 = new CheckBox();
checkbox5.Location = new Point(195, 275);
checkbox5.Text = "HTML";
this.Controls.Add(checkbox5);
}
}
}

Output:

Conclusion – Checkbox in C#

A checkbox in C# can also have an indeterminate state. This can be achieved by setting the CheckState property to ‘Indeterminate. It is a state between ‘Yes’ and ‘No’ in which the checkbox will neither be checked nor unchecked.

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