限制TextBox只能输入数字

方法1：屏蔽用户除了数字键以外的输入。前提ImeMode   =   Disable让用户无法切换中文或其他输入法。  
    Private Sub TextBox1_KeyPress(ByVal sender As System.Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles TextBox1.KeyPress
        If Char.IsNumber(e.KeyChar) Or e.KeyChar = Chr(Keys.Back) Then   '退格应该允许。  
            Return
        End If
        e.Handled = True
    End Sub
如果允许用户输入小数,则可以这样:
    Private Sub TextBox1_KeyPress(ByVal sender As System.Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles TextBox1.KeyPress
        If Char.IsNumber(e.KeyChar) Or e.KeyChar = Chr(Keys.Back) Or e.KeyChar = "." Then  
            Return
        End If
        e.Handled = True
    End Sub

 方法2：在TextBox的Validing事件用正则表达式验证。
    Private Sub textBox1_Validating(ByVal sender As Object,ByVal e As System.ComponentModel.CancelEventArgs) Handles TextBox1.Validating
        Dim numericRegex As Regex = New Regex("^/d+$")
        If numericRegex.IsMatch(CType(sender, TextBox).Text) = False Then
            e.Cancel = True
            TextBox1.Select(0, TextBox1.Text.Length)
        End If
    End Sub

方法3:不需要对用户的输入做任何控制,等待用户输入完成后再进行验证
        If IsNumeric(TextBox1.Text) = False Then
            MsgBox("请输入有效数字值!")
        End If