验证18位身份证号码

老师好！请教我在窗体身份证号码字段如何搞呀？ 

'函数名称：    IsIDNumber
'功能描述：    根据GB11643-1999编码规则验证18位身份证号码是否有效
'输入参数：    参数1：IDNumber    必需的，18位身份证号码
'返回参数：    有效返回True,无效返回False
'兼 容 性：
'使用示例：    IsIDNumber("370284197901130819") '返回True
'相关调用：
'作    者：    红尘如烟
'创建日期：    20010-4-25
'===================================================================
Function IsIDNumber(ByVal IDNumber As String) As Boolean
    Const W As String = "79058421637905842"     '加权因子
    Const C As String = "10X98765432"           '校验码
    Dim S As Integer, i As Integer, T As Integer
   
    IDNumber = UCase(Trim(IDNumber))
    If Len(IDNumber) <> 18 Then Exit Function
    If Not IsNumeric(Mid(IDNumber, 1, 17)) Then Exit Function
    If Not IDNumber Like "*[0-9X]" Then Exit Function

    For i = 1 To 17
        T = Mid(W, i, 1)
        If T = 0 Then T = 10
        S = S + Mid(IDNumber, i, 1) * T
    Next
    T = S Mod 11
    If Right(IDNumber, 1) = Mid(C, T + 1, 1) Then IsIDNumber = True
End Function