只接受文本框中的数字

Question

给定一个texbox,我怎样才能完全忽略非数字字符？因此,如果我按"A"或"Z",这些字符将永远不会出现在文本框中.如果用户试图输入数字并且他试图输入非数字,我想运行一些代码.

Answer 1

试试这个

Private Sub textBox1_KeyPress(sender As Object, e As KeyPressEventArgs) Handles textBox1.KeyPress
    If Char.IsDigit(e.KeyChar) Then
        e.Handled = False
    Else
        e.Handled = True
    End If

End Sub

如果e.Handled对于非数字设置为true,则没有输入将转到文本框; 否则事件消息会像往常一样流动.

编辑:

要处理BackSpace和删除是一个更多的工作,但你可以试试这个

Private Sub textBox1_KeyPress(sender As Object, e As KeyPressEventArgs) Handles textBox1.KeyPress
    If Char.IsDigit(e.KeyChar) OrElse e.KeyChar = CChar(Keys.Delete) OrElse e.KeyChar = CChar(Keys.Back) Then
        e.Handled = False
    Else
        e.Handled = True
    End If

End Sub

Protected Overrides Function ProcessCmdKey(ByRef msg As Message, keyData As Keys) As Boolean
    If keyData = Keys.Delete OrElse keyData = Keys.Back Then
        OnKeyPress(New KeyPressEventArgs(CChar(keyData))
    End If

    Return MyBase.ProcessCmdKey(msg, keyData)
End Function

对于Delete和Backspace键不会触发KeyPress事件,因此重写ProcessCmdKey以手动调用表单的OnKeyPress()