Password Validation in C#

Submitted by janobe on Saturday, May 18, 2019 - 01:22.

Today, you will learn how to create a password validation textbox in c#. This procedure illustrates how to validate a textbox at least 8 to 15 charters and it's composed of at least one upper case and numbers. This is very helpful for you when you have to restrict your textbox password.

Creating Application

Step 1

Open Microsoft Visual Studio 2015 and create a new windows form application for c#. ps1

Step 2

Do the form just like shown below. ps2

Step 3

Press F7 to open the code editor. In the code editor, add a namespace to access regular expression libraries.

  
using System.Text.RegularExpressions;

Step 4

Create a method for password validation.

   
        private static Regex PasswordValidation()
        {
            string pattern = "(?!^[0-9]*$)(?!^[a-zA-Z]*$)^([a-zA-Z0-9]{8,15})$";
 
            return new Regex(pattern, RegexOptions.IgnoreCase);
        }

Step 5

Initialize the method that you have created.

   
        static Regex vaildate_password = PasswordValidation();

Step 6

Write the following code to verify a password in a textbox when the button is clicked.

     
        private void button1_Click(object sender, EventArgs e)
        {
            if (vaildate_password.IsMatch(textBox1.Text) != true)
            {
                MessageBox.Show("Password must be atleast 8 to 15 characters. It contains atleast one Upper case and numbers.", "Invalid", MessageBoxButtons.OK, MessageBoxIcon.Exclamation);
                textBox1.Focus();
                return;
            }
            else
            {
                MessageBox.Show("Password is correct.");
            }
        }

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