Extract Numbers from alphanumeric strings

Function NUMINSTR(ByVal str As String, Optional ByVal idx As Integer = 1) As Double
    Dim first As Integer
    Dim last As Integer
    Dim test As String
    Dim a As String
    Dim x As Integer
    Dim z As Integer
    Dim StartVal As Integer
    
    StartVal = 1
    test = "0123456789."
    
    
    If Len(str) = 0 Then
        NUMINSTR = Null
        Exit Function
    End If
    
    For z = 1 To idx
    
        If z > 1 Then StartVal = last + 1
            
        If StartVal > Len(str) Then
            NUMINSTR = Null
            Exit Function
        End If
        
        For x = StartVal To Len(str)
            a = Mid(str, x, 1)
            If InStr(test, a) > 0 Then
                first = x
                Exit For
            End If
        Next x
        
        If first = 0 Then
            NUMINSTR = Null
            Exit Function
        End If
        
        last = Len(str) + 1
        
        For x = first To Len(str)
            a = Mid(str, x, 1)
            If InStr(test, a) = 0 Then
                last = x
                Exit For
            End If
        Next x
    
    Next z
    
    NUMINSTR = val(Mid(str, first, last - first))
    
End Function

Function NUMINSTR(ByVal str As String, Optional ByVal idx As Integer = 1)
Dim oMatches As Object
 
With CreateObject("vbscript.regexp")
    .Pattern = "\d+"
    .Global = True
    Set oMatches = .Execute(str)
    If oMatches.Count >= idx Then NUMINSTR = oMatches(idx - 1) Else NUMINSTR = ""
End With
End Function