How to Highlight the Text Present in the MaskedTextBox in C#?

In C#, MaskedTextBox control gives a validation procedure for the user input on the form like date, phone numbers, etc. Or in other words, it is used to provide a mask which differentiates between proper and improper user input. In MaskedTextBox control, you can highlight the selected text present in the MaskedTextBox control when the MaskedTextBox control loses its focus using HideSelection Property provided by the MaskedTextBox control.
If the value of this property is true, then the selected text present in the MaskedTextBox is not highlighted when the control loses its focus. And if the value of this property is false, then the selected text present in the MaskedTextBox is highlighted when the control loses its focus. The default value of this property is true. You can set this property in two different ways:

1. Design-Time: It is the easiest way to set the value of HideSelection property of MaskedTextBox control as shown in the following steps:

• Step 1: Create a windows form as shown in the below image:
  Visual Studio -> File -> New -> Project -> WindowsFormApp
  
• Step 2: Next, drag and drop the MaskedTextBox control from the toolbox on the form as shown in the below image:

  

• Step 3: After drag and drop you will go to the properties of the MaskedTextBox and set the value of HideSelection property of MaskedTextBox control as shown in the below image:

  

  Output:

  

2. Run-Time: It is a little bit trickier than the above method. In this method, you can set the value of HideSelection property of the MaskedTextBox control programmatically with the help of given syntax:

public bool HideSelection { get; set; }

The value of this property is of System.Boolean type, either true or false. The following steps show how to set the value of HideSelection property of the MaskedTextBox control dynamically:

• Step 1: Create a MaskedTextBox using the MaskedTextBox() constructor is provided by the MaskedTextBox class.

  // Creating a MaskedTextBox
  MaskedTextBox m = new MaskedTextBox();
  

• Step 2: After creating MaskedTextBox, set the HideSelection property of the MaskedTextBox provided by the MaskedTextBox class.

  // Setting the HideSelection property
  m.Mask = "000000000";
  

• Step 3: And last add this MaskedTextBox control to the form using the following statement:

  // Adding MaskedTextBox control on the form
  this.Controls.Add(m);
  

  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 WindowsFormsApp39 {
  
  public partial class Form1 : Form {
  
      public Form1()
      {
          InitializeComponent();
      }
  
      private void Form1_Load(object sender, EventArgs e)
      {
          // Creating and setting the
          // properties of the Label
          Label l1 = new Label();
          l1.Location = new Point(413, 98);
          l1.Size = new Size(176, 20);
          l1.Text = " Example";
          l1.Font = new Font("Bell MT", 12);
  
          // Adding label on the form
          this.Controls.Add(l1);
  
          // Creating and setting the
          // properties of the Label
          Label l2 = new Label();
          l2.Location = new Point(242, 135);
          l2.Size = new Size(126, 20);
          l2.Text = "Phone number:";
          l2.Font = new Font("Bell MT", 12);
  
          // Adding label on the form
          this.Controls.Add(l2);
  
          // Creating and setting the
          // properties of the MaskedTextBox
          MaskedTextBox m = new MaskedTextBox();
          m.Location = new Point(374, 137);
          m.Mask = "000000000";
          m.Size = new Size(176, 20);
          m.Name = "MyBox";
          m.BorderStyle = BorderStyle.Fixed3D;
          m.HideSelection = true;
          m.Font = new Font("Bell MT", 18);
  
          // Adding MaskedTextBox
          // control on the form
          this.Controls.Add(m);
      }
  }
  }

  Output: