如何在visual basic中控制循环..我在登录尝试时使用它

Question

我有这个项目，我正在尝试用最短的代码创建一个Login Attempt / s，所以我尝试使用循环。这是编码

Private Sub btnLogin_Click(sender As Object, e As EventArgs) Handles btnLogin.Click
    Dim attempts = 3
    Do
        If txtUsername.Text = username And txtPassword.Text = password Then
            MessageBox.Show("ACCESS GRANTED")
            Me.Hide()
            MainMenu.Show()
        Else
            MessageBox.Show("ACCESS DENIED")
            txtUsername.Text = "input username"
            txtPassword.Text = "input password"
            attempts = attempts - 1
        End If

    Loop Until attempts <= 0
    MessageBox.Show("Maximum Login Attempts Reached!")
End Sub

但似乎我处于悖论或无限循环中。我正在考虑像继续一样控制循环;并打破;像java那样..有什么方法可以在visual basic中做到这一点？

Answer 1

正如汉斯指出的那样，你需要将attempt移到方法之外。只需在表单Class中创建变量，然后使用每个onClick事件进行尝试。希望这是有道理的，下面的代码应该给你想要的结果！

Dim Attempts As Integer = 0

Private Sub btnLogin_Click(sender As Object, e As EventArgs) Handles btnLogin.Click
    Attempts += 1
    If Attempts > 3 Then
        MessageBox.Show("Maximum Login Attempts Reached!")
        Exit Sub
        'User has tried too many times - just keep exiting the method, or you can use
        'Application.Exit()
        'This will just quit the program..
    End If

    If txtUsername.Text = username And txtPassword.Text = password Then
        MessageBox.Show("ACCESS GRANTED")
        Me.Hide()
        MainMenu.Show()
    Else
        MessageBox.Show("ACCESS DENIED")
        txtUsername.Text = "input username"
        txtPassword.Text = "input password"
    End If
End Sub

如果你想让应用程序退出，那么取消对Application.Exit的注意，并注释掉Exit Sub，如果你想重置尝试（无论出于什么原因）你可以在调用Attempts = 0时添加

Hth Chicken