首先 - 我是学生，这是我的Capstone项目。我不想要代码作为答案，只需要一个森林指南。
我正在编写一个包含主表单和辅助表单的VB.Net应用程序。在主窗体上是用于输入信息的控件（按钮和文本框）（电子邮件和密码。换句话说，登录屏幕），我使用textchanged子来知道何时在文本框中输入了信息并尝试使用Keypress限制输入。这不是我想要的。我昨天花了很多时间研究和尝试不同的方法。只会让自己更加困惑。需要一些建议。
底线是 - 作为一个独立的子键，按键效果非常好，但按钮点击不能按预期运行。当我制作textchanged sub的按键部分时，它立即向南移动。我收到强制转换异常，但没有错误代码或其他错误指示。
我的首选是在textchanged子中使用按键 我希望textchenged sub监听要更改的文本框，然后由按键控制。
我做错了什么？
这个子程序没有像我认为的那样运行......
Private Sub txtemailid_TextChanged(ByVal o As [Object], ByVal e1 As KeyPressEventArgs) Handles txtemailid.TextChanged
'Dim ac As String = "@"
If e.KeyChar <> ChrW(Keys.Back) Then
If Asc(e.KeyChar) < 97 Or Asc(e.KeyChar) > 122 Then
If Asc(e.KeyChar) <> 46 And Asc(e.KeyChar) <> 95 Then
If Asc(e.KeyChar) < 48 Or Asc(e.KeyChar) > 57 Then
If ac.IndexOf(e.KeyChar) = -1 Then
e.Handled = True
Else
If txtemailid.Text.Contains("@") And e.KeyChar = "@" Then
e.Handled = True
End If
End If
End If
End If
End If
End If
End Sub
以下子工作效果非常好，但会干扰窗体上的按钮控件....
Private Sub txtemailid_KeyPress(ByVal sender As System.Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles txtemailid.KeyPress
'* Method txtemailid_KeyPress()
'* Version: 1.00.00
'* Author: Ed Petry
'* Date: March-2, 2017
'*
'* Description:
'* Intercepts the key presses as entered, allowing only acceptable characters to be entered.
'* code will only allow user To input a-z(small), 0 To 9(digits), @,.,
Dim ac As String = "@"
If e.KeyChar <> ChrW(Keys.Back) Then
If Asc(e.KeyChar) < 97 Or Asc(e.KeyChar) > 122 Then
If Asc(e.KeyChar) <> 46 And Asc(e.KeyChar) <> 95 Then
If Asc(e.KeyChar) < 48 Or Asc(e.KeyChar) > 57 Then
If ac.IndexOf(e.KeyChar) = -1 Then
e.Handled = True
Else
If txtemailid.Text.Contains("@") And e.KeyChar = "@" Then
e.Handled = True
End If
End If
End If
End If
End If
End If
End Sub
下面的其他说明
是的，允许使用国会大厦的字母，但教练是“好的”＃39;只有要求小写的。
以下是典型的按钮子例程（我已经提交＆＃39;，＆＃39;清除表单＆＃39;并取消＆＃39;用于所述功能。此外，表单有＆＃39 ;创建帐户＆＃39;忘记密码＆＃39;按钮。这些按钮导致单件设计表单允许该功能（创建或恢复）。
Private Sub btnSubmit_Click(sender As Object, e As EventArgs) Handles btnSubmit.Click
'* Method: btnSubmit_Click
'* Version: 1.00.00
'* Author: Ed Petry
'* Date: February-23, 2017
'*
'* Description:
'* Intercept user's request to submit information in attempt to login.
'** MAY KEEP THIS MAY NOT Throw up a Message Box to confirm that's what the operator
'** MAY KEEP THIS MAY NOT wants to do. If so, cancel the login attempt and return to the initial state.
Try
' try is placeholder to verify logic is correct.
If MsgBox("Is your information correct?", MsgBoxStyle.YesNo) = MsgBoxResult.Yes Then
' Submit username and password informtion to business layer for verification of membership
End If
Catch ex As Exception
' An error occured! Show the error to the user and then exit.
MessageBox.Show(ex.Message)
End Try
End Sub
补充评论---
这是输入信息后我正在使用的验证子。这很好..
' uses validating event of textbox control to validate the email id using regular expression
Private Sub txtemailAddress_Validating(ByVal sender As System.Object, ByVal e As System.ComponentModel.CancelEventArgs) Handles txtEmailAddress.Validating
Dim pattern As String = "^[A-Z][A-Z|0-9|]*[a-z][a-z|0-9|]*([_][a-z|0-9]+)*([.][a-z|0-9]+([_][a-z|0-9]+)*)?@[a-z][a-z|0-9|]*\.([a-z][a-z|0-9]*(\.[a-z][a-z|0-9]*)?)$"
Dim match As System.Text.RegularExpressions.Match = System.Text.RegularExpressions.Regex.Match(txtEmailAddress.Text.Trim(), pattern, RegexOptions.IgnoreCase)
If (match.Success) Then
MessageBox.Show("Success", "Checking")
Else
MessageBox.Show("Please enter a valid email address", "Checking")
With txtEmailAddress
.Clear()
.Focus()
End With
End If
End Sub