private void button1_Click(object sender, EventArgs e)

  {
    String name = this.textBox1.Text; // 获取里面的值
    String password = this.textBox1.Text;
    if (name.Equals("admin") && password.Equals("admin")) // 判断账号密码是否等于admin
    {
      MessageBox.Show("登录成功");
    }
    else {
      MessageBox.Show("登录失败！");
    }
  }

 //限定用户名必须为字母
     private void txtName_KeyPress(object sender, KeyPressEventArgs e)
     {
       if ((e.KeyChar >= 'a' && e.KeyChar <= 'z') || (e.KeyChar >= 'A' && e.KeyChar <= 'Z'))
       {
         e.Handled = false;
       }
       else {
         MessageBox.Show("用户名只能为字母！");
         e.Handled = true;
       }
     }

  //光标进入文本框时，背景为蓝色，字体为白色；
     //光标离开文本框时，背景为白色，字体为黑色。
     private void txtName_Enter(object sender, EventArgs e)
     {
       txtName.ForeColor = Color.White;
       txtName.BackColor = Color.Blue;
     }
 
     private void txtName_Leave(object sender, EventArgs e)
     {
       txtName.BackColor = Color.White;
       txtName.ForeColor = Color.Black;
     }

private void btnLogin_Click(object sender, EventArgs e)
    {
      string userName = txtName.Text;
      string password = txtPwd.Text;
      if (userName == "admin" && password == "123")
      {
        MessageBox.Show("欢迎进入个人理帐系统！", "登陆成功！", MessageBoxButtons.OK, MessageBoxIcon.Information);
      }
      else
      {
        MessageBox.Show("您输入的用户名或密码错误！", "登录失败！", MessageBoxButtons.OK, MessageBoxIcon.Exclamation);
      }
    }

 private void btnCancel_Click(object sender, EventArgs e)
    {
      txtName.Text = "";
      txtPwd.Text = "";
      txtName.Focus();
    }