c# Tutorial : How write a password protected application

In this tutorial i will show you what can we write an application that protected with username and password. Let's start.

First we make a project.
Then we make the design of the loging form.(we required 2 textbox that called txtUser,and txtPass, 1 checkbox, 1 button that I called btnLogin and some label.)
That's mine : 

then we can start the designing of the main form( the main form we can see after logging in)

The code :

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
namespace password_protect_application{
        public partial class Form1 : Form
        {
                Form2 mainform = new Form2();
                public Form1()
                {
                        InitializeComponent();
                }

                private void Form1_Load(object sender, EventArgs e)
                {
                }
                private void btnLogin_Click(object sender, EventArgs e)
                {
                        //the checking method
                        //you can put into the bracket the password,and username what you want
                        if (txtUser.Text.ToString().CompareTo("test") == 0 & txtPass.Text.ToString().CompareTo("test") == 0)
                        {
                                MessageBox.Show("Login Sucessfull.Click OK to continue", "Login", MessageBoxButtons.OK, MessageBoxIcon.Information);
                                this.Hide();     //hide the login form
                                mainform.Show(); //& show the main form 
                        }
                        else
                        {
                                MessageBox.Show("Wrong Username/Password! n Please try again!", "Login", MessageBoxButtons.OK, MessageBoxIcon.Error);
                                txtPass.Text = ""; //delete writed password
         
                      txtUser.Text = ""; //delete writed username
                        }
                }

                private void checkBox1_CheckedChanged(object sender, EventArgs e)
                {
                        if (checkBox1.Checked == true)
                        {
                                txtPass.PasswordChar = '*'; //set passwordchar to '*'
                                checkBox1.Text = "Show password"; //change checkbox text to show password
                        }
                        else 
                        {
                                txtPass.PasswordChar = (char)0; //reset passwordchar to default
                                checkBox1.Text = "Hide password"; //change password to hide password
                        }
                }

        }
}

This source code content a password hide/show function also :
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