LabExer5_Login.cs

using System;
using System.Windows.Forms;
using System.Drawing;
using System.IO;

namespace MyForm
{
    public class Login : Form
    {
        private Button btLogin;
        private Button btIndex;
        private TextBox username;
        private TextBox password;
        private Label un;
        private Label pw;
        private CheckBox chPass;


        public Login()
        {
            InitializeComponents();
        }

        public void InitializeComponents()
        {
            this.Text = "Login Form";
            this.BackColor = Color.Lavender;
            this.ForeColor = Color.Black;
            this.Size = new Size(250, 300);
            this.StartPosition = FormStartPosition.CenterScreen;


            btLogin = new Button();
            btLogin.Text = "Login";
            btLogin.Location = new Point(80, 180);
            btLogin.Click += btLogin_Click;

            btIndex = new Button();
            btIndex.Text = "Back";
            btIndex.Location = new Point(80, 210);
            btIndex.Click += btIndex_Click;

            un = new Label();
            un.Text = "Username";
            un.Location = new Point(20, 80);

            username = new TextBox();
            username.Text = "";
            username.MaxLength = 10;
            username.Location = new Point(80, 80);

            pw = new Label();
            pw.Text = "Password";
            pw.Location = new Point(20, 110);

            password = new TextBox();
            password.Text = "";
            password.UseSystemPasswordChar = true;
            password.Location = new Point(80, 110);

            chPass = new CheckBox();
            chPass.Location = new Point(79, 130);
            chPass.Text = "Show Password";
            chPass.UseVisualStyleBackColor = true;
            chPass.CheckedChanged += new System.EventHandler(chPass_CheckedChanged);

            this.Controls.Add(username);
            this.Controls.Add(password);
            this.Controls.Add(btLogin);
            this.Controls.Add(un);
            this.Controls.Add(pw);
            this.Controls.Add(chPass);
            this.Controls.Add(btIndex);
        }

        public void btLogin_Click(object sender, EventArgs e)
        {
            string path = String.Concat("", username.Text, ".txt");
            string[] user = new string[2];

            if (username.Text == "" || password.Text == "")
            {
                MessageBox.Show("No username/password. \nPlease input your log-in credentials.", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
                return;
            }

            if (!File.Exists(path))
            {
                MessageBox.Show("Please input a valid username.", "Invalid Username", MessageBoxButtons.OK, MessageBoxIcon.Error);
                return;
            }
            else
            {
                using (StreamReader sr = new StreamReader(path))
                {
                    for (int i = 0; i < user.Length; i++)
                    {
                        user.SetValue(sr.ReadLine(), i);
                    }
                }
                if ((string)(user.GetValue(0)) != password.Text)
                {
                    MessageBox.Show("Please input the correct password.", "Incorrect Password", MessageBoxButtons.OK, MessageBoxIcon.Error);
                    return;
                }
                else
                {
                    if ((string)(user.GetValue(1)) == "Type One")
                    {
                        TypeOne one = new TypeOne();
                        this.Hide();
                        one.Show();
                    }
                    else
                    {
                        password.UseSystemPasswordChar = true;
                        TypeTwo two = new TypeTwo();
                        this.Hide();
                        two.Show();

                    }
                }
            }
        }

        public void btIndex_Click(object sender, EventArgs e)
        {
            Index ind = new Index();
            ind.Show();
            this.Hide();

        }

        private void chPass_CheckedChanged(object sender, EventArgs e)
        {
            if (chPass.CheckState == CheckState.Checked)
                password.UseSystemPasswordChar = false;
            else
                password.UseSystemPasswordChar = true;
        }
    }
}