vb.net 如何避免在 Windows 应用程序的文本框中使用特殊字符
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原文地址: http://stackoverflow.com/questions/19486244/
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How to avoid taking special characters in textbox of a Windows application
提问by Nilesh B
I am developing the Windows application. I have a form and I am trying to validate the text box on that form.
我正在开发 Windows 应用程序。我有一个表单，我正在尝试验证该表单上的文本框。
I want to put some validation on a text box like the text box should accept only Alphabates, Didgits and comma.(No other characters like special symbols.) As well, it should accept the Enter key when cursor is in that text box.
我想对文本框进行一些验证，例如文本框应该只接受 Alphabates、Didgits 和逗号。（没有其他字符，如特殊符号。）此外，当光标位于该文本框中时，它应该接受 Enter 键。
I am trying to write the code but some how its not working. But its still taking special characters like <>/;' What changes I have to made ?
我正在尝试编写代码，但有些方法不起作用。但它仍然采用特殊字符，如 <>/;' 我必须做出哪些改变？
here is the code...
这是代码...
Key Down Event
按键按下事件
Private Sub txtOLDBuildingName_KeyDown(sender As Object, e As KeyEventArgs) Handles txtOLDBuildingName.KeyDown
' Initialize the flag to false.
nonNumberEntered = False
' Determine whether the keystroke is a number from the top of the keyboard.
If (e.KeyCode < Keys.D0 And e.KeyCode > Keys.D9) And (e.KeyCode > Keys.A And e.KeyCode < Keys.Z) Then
nonNumberEntered = True
End If
'If shift key was pressed, it's not a number.
If Control.ModifierKeys = Keys.Shift Then
nonNumberEntered = True
End If
End Sub
Key Press Event
按键事件
Private Sub txtOLDBuildingName_KeyPress(sender As Object, e As KeyPressEventArgs) Handles txtOLDBuildingName.KeyPress
If nonNumberEntered = True Then
e.Handled = True
End If
End Sub
回答by ElektroStudios
Delete the sub which is handling KeyDownevent and replace the sub which is handling KeyPressevent to this one:
删除正在处理KeyDown事件的 sub 并将正在处理事件的 sub 替换KeyPress为这个：
ReadOnly ValidChars As String = _
"abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789,"
Private Sub txtOLDBuildingName_KeyPress(ByVal sender As Object, ByVal e As KeyPressEventArgs) _
Handles txtOLDBuildingName.KeyPress
e.Handled = Not (ValidChars.IndexOf(e.KeyChar) > -1 _
OrElse e.KeyChar = Convert.ToChar(Keys.Back))
End Sub
Update:
更新：
This modification is more precise, it compares the clipbard content before paste them.
这种修改更精确，它在粘贴之前比较剪贴板内容。
ReadOnly AllowedKeys As String = _
"abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789,"
Private Sub TextBox1_KeyPress(ByVal sender As Object, ByVal e As KeyPressEventArgs) Handles TextBox1.KeyPress
Select Case e.KeyChar
Case Convert.ToChar(Keys.Enter) ' Enter is pressed
' Call method here...
Case Convert.ToChar(Keys.Back) ' Backspace is pressed
e.Handled = False ' Delete the character
Case Convert.ToChar(Keys.Capital Or Keys.RButton) ' CTRL+V is pressed
' Paste clipboard content only if contains allowed keys
e.Handled = Not Clipboard.GetText().All(Function(c) AllowedKeys.Contains(c))
Case Else ' Other key is pressed
e.Handled = Not AllowedKeys.Contains(e.KeyChar)
End Select
End Sub
