Calling CompareStringEx from Visual Basic 6

CompareStringEx_from_VB6.vb

Private Declare Function CompareStringEx Lib "kernel32.dll" ( _
    ByRef lpLocaleName As String, _
    ByVal dwCmpFlags As Long, _
    ByRef lpString1 As Byte, _
    ByVal cchCount1 As Long, _
    ByRef lpString2 As Byte, _
    ByVal cchCount2 As Long, _
    ByVal lpVersionInformation As Long, _
    ByVal lpReserved As Long, _
    ByVal lParam As Long) As Long

' Compares two strings, returning signed result like StrComp does
' 2019-10-29 JmW
Public Function ApiCompareStringDigitsAsNumbers(String1 As String, String2 As String) As Integer
    Const LOCALE_NAME_USER_DEFAULT = vbNullString
    Const SORT_DIGITSASNUMBERS As Long = 8 ' dwCmpFlags        
        
    If CSW_OK Then ' Earlier check for function in kernel32.dll -- still have XP users
        Dim lpString1() As Byte
        Dim lpString2() As Byte
        Dim result As Long
        
        lpString1 = String1 & vbNullChar
        lpString2 = String2 & vbNullChar
        
        result = CompareStringEx( _
            LOCALE_NAME_USER_DEFAULT, _
            SORT_DIGITSASNUMBERS, _
            lpString1(0), -1, _
            lpString2(0), -1, _
            0, 0, 0)
        ' The function returns 0 if it does not succeed.
        ' Returns one of the following values if successful:
        ' CSTR_LESS_THAN, CSTR_EQUAL, CSTR_GREATER_THAN
        ' To maintain the C runtime convention of comparing strings, the value 2
        ' can be subtracted from a nonzero return value.
        ' Then, the meaning of <0, ==0, and >0 is consistent with the C runtime.
        If result <> 0 Then
            ApiCompareStringDigitsAsNumbers = result - 2
            Exit Function
        End If
       
    End If
    
    ' If something dailed or API wasn't actually there, then default to
    ' calling StrComp
    ApiCompareStringDigitsAsNumbers = StrComp(String1, String2, vbTextCompare)
End Function