private void btnGiris_Click(object sender, EventArgs e) { UserManager userManager = new UserManager(); List <User> users = new List <User>(); users = userManager.GetList(); AdminManager adminManager = new AdminManager(); List <Admin> admins = new List <Admin>(); admins = adminManager.GetList(); AccountingManager accountingManager = new AccountingManager(); List <Accounting> accountings = new List <Accounting>(); accountings = accountingManager.GetList(); int i = 0; foreach (var admin in admins) { if (txtKullaniciAdi.Text == admin.AdminTcNo && txtSifre.Text == admin.AdminSifre) { AdminForm adminForm = new AdminForm(users, i); adminForm.Show(); this.Hide(); } i++; } i = 0; foreach (var user in users) { if (txtKullaniciAdi.Text == user.KullaniciAdi && txtSifre.Text == user.Sifre) { UserForm userForm = new UserForm(users, i); userForm.Show(); this.Hide(); } i++; } i = 0; foreach (var account in accountings) { if (txtKullaniciAdi.Text == account.KullaniciAdi && txtSifre.Text == account.Sifre) { AccountingForm accountingForm = new AccountingForm(accountings, i); accountingForm.Show(); this.Hide(); } i++; } }