How to set Read-Only content in 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 are allowed to set the text in the MaskedTextBox for read-only using ReadOnly Property. If the value of this property is true, then the text present in the MaskedTextBox is read-only. Otherwise, false. The default value of this property is false. You can set this property in two different ways:

1. Design-Time: It is the easiest way to set the value of ReadOnly 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 ReadOnly 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 ReadOnly property of the MaskedTextBox control programmatically with the help of given syntax:

public bool ReadOnly { 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 ReadOnly 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 ReadOnly property of the MaskedTextBox provided by the MaskedTextBox class.

  // Setting the ReadOnly property
  m.ReadOnly = true;
  

• 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 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 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.Text = "999999999";
          m.ReadOnly = true;
          m.Font = new Font("Bell MT", 18);
  
          // Adding MaskedTextBox
          // control on the form
          this.Controls.Add(m);
      }
  }
  }

  Output: