Vb.net
代码
Private Sub TextBox1_KeyPress(ByVal sender As Object,ByVal e As System.Windows.Forms.KeyPressEventArgs)
Handles TextBox1.KeyPress,TextBox2.KeyPress,TextBox3.KeyPress
'判断输入的是否是数字、小数点或“BackSpace”符号
If Char.IsDigit(e.KeyChar) Or e.KeyChar = "." Or e.KeyChar = Chr(8) Then
'判断输入的小数点是否唯一
If e.KeyChar = "." And InStr(CType(sender,TextBox).Text,".") > 0 Then
e.Handled = True
Else
e.Handled = False
End If
'判断输入的负号是否是在第一位
ElseIf e.KeyChar = "-" And CType(sender,TextBox).Text = "" Then
e.Handled = False
Else
e.Handled = True
End If
End Sub
http://sheng.iteye.com/blog/720795