Question

vb.net中限制只输入小写字母

Public Class Form1
Private Sub TextBox1_KeyPress(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles TextBox1.KeyPress
Dim keyascii As Integer
If keyascii > 122 Or keyascii < 97 Then
keyascii = 0
End If
End Sub
End Class

Answer 1

不用这个应该使用重载Form的ProcessCmdKey，假如我们处理的是textBox1如下： Protected Overrides Function ProcessCmdKey(ByRef msg As Message, ByVal keyData As Keys) As Boolean
If Not TextBox1.Focused Then Return False '焦点不在指定文本框上，不处理
If keyData >= Keys.A And keyData <= Keys.Z Then '是字母，还不知道是否是大小写
If IsKeyLocked(Keys.CapsLock) Then '大写锁定
Return Not CInt(ModifierKeys()) And CInt(Keys.Shift) <> 0 '如果Shift没锁定（即是大写）要过滤，返回TRUE;
Else
Return CInt(ModifierKeys()) And CInt(Keys.Shift) <> 0 '如果Shift锁定（即是大写）要过滤，返回TRUE;
End If
ElseIf keyData = Keys.Back Or keyData = Keys.Delete Then '还有允许的其它键
Return False
End If
Return True '剩余的键都过滤掉
End Function

Answer 2

可以使用keydown事件 Private Sub TextBox1_KeyDown(ByVal sender As System.Object, ByVal e As System.Windows.Forms.KeyEventArgs) Handles TextBox1.KeyDown
If e.KeyCode < Keys.A + 32 Or e.KeyCode > Keys.Z + 32 Then '如果不是小写
If e.KeyCode <> Keys.Delete And e.KeyCode <> Keys.Back And e.KeyCode <> Keys.Right And e.KeyCode <> Keys.Left Then' 还是不Del,Backspace,也不是左右箭头,
e.Handled = True 把这个属性置为True就取消了这次按键
End If
End If
End Sub

Answer 3

Private Sub TextBox1_KeyPress(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles TextBox1.KeyPress
select case e.keycharcase "a" to "z"case chr(8) 'Backspace Keycase else e.handled=trueend selectEnd Sub