Diplom_B/LoginForm.cs

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 Diplom_B
{
	public partial class LoginForm : Form
	{
		public LoginForm()
		{
			InitializeComponent();
			this.CenterToScreen();
			label3.Text = "";
		}

		private void button1_Click(object sender, EventArgs e)
		{
			label3.Text = "";
			var usr = new User(comboBox1.Text, comboBox1.Text);
			if (!usr.CheckUser())
			{
				label3.Text = "Пользователя нет";
				return;
			}
			if (!usr.Login())
			{
				label3.Text = "Неверный пароль";
				return;
			}

			Program.user = usr;

			this.Hide();
			var izdForm = new IzdForm();
			izdForm.Closed += (s, args) => this.Close();
			izdForm.Show();
		}
	}
}