给一个文本框，只能输入数字、小数点和负号，其他的按键输入将不显示。
1.普通程序代码控制
Private Sub TextBox1_KeyPress(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles TextBox1.KeyPress
Dim c As Char
c = e.KeyChar
If c = "."c Then
If InStr(TextBox1.Text, e.KeyChar) > 0 Or (InStr(TextBox1.Text, "-") > 0) And (TextBox1.SelectionStart = 0) Then
e.KeyChar = ""
End If
ElseIf c = "-"c Then
If InStr(TextBox1.Text, c) > 0 Or TextBox1.SelectionStart > 0 Then
e.KeyChar = ""
End If
ElseIf c = "0"c Then
If (TextBox1.SelectionStart = 0 And Not TextBox1.Text.StartsWith("0") And TextBox1.Text.Length <> 0) Or (TextBox1.SelectionStart <= 1 And TextBox1.Text.StartsWith("0")) Then
e.KeyChar = ""
End If
ElseIf c = ControlChars.Back Then
ElseIf InStr("123456789", e.KeyChar) <= 0 Then
e.KeyChar = ""
End If
End Sub
2.正则表达式控制//正则表达式不对
Private Sub TextBox2_KeyPress(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles TextBox2.KeyPress
'利用正则表达式验证
'System.Text.RegularExpressions.Regex.IsMatch(TextBox2.Text, "^(-?\\d+)(\\.\\d+)?$") ''''该表达式来源与网上，未经证实
End Sub
// ^[+-]?(?:\d+\.?\d*|\d*\.?\d+)[\r\n]*$ 据说这个是对的。未验证。
3.使用MaskedTextBox//不能输入-和。
Mask属性设置的是自定义掩码为999999999999999
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将窗体中所有TextBox的text全部清空，其他的CheckBox啊RadioButton啊这些照旧
Private Sub Button1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim tp As TabPage
Dim text As Control
For Each tp In TabControl1.TabPages
For Each text In tp.Controls
If TypeOf text Is TextBox Then
text.Text = ""
End If
Next
Next
End Sub
