Dynamic arrays: what do you think about this scheme?

[krtxmrtz]

I have been thinking about the most convenient way to use dynamic arrays so that memory can be efficiently used. The following code is an example borrowed from an application I'm working on. Aside from the fact that it doesn't care about the total amount of computer memory it seems to work very nicely.

However, I'd like to hear the gurus' opinion: is it formally correct or does it have some conceptual flaw that I have overlooked?

'(In the declarations section)
Const DeltaDim=100
Dim MaxNum As Integer
Dim x() As single, y() as single
______________________________________________________________________
 
Sub SomeName()    
'This subroutine reads a (very large) number of x & y coordinates from a text file
    Dim ff As Integer
    Dim nl as integer
    Dim k as integer
    Dim TxtLin as string
'Initialize array dimension to some convenient value
    MaxNum=1000
    Redim x(1 To MaxNum), y(1 To MaxNum)
'Initialize line counter
    nl = 0
    ff = FreeFile
'(FileName is assumed to be assigned elsewhere)
    Open FileName For Input As #ff
        While Not EOF(ff)
            Line Input #ff, TxtLin
            nl=nl+1
'This is the relevant section: incresing the
'arrays' dimensions as needed
            If nl > MaxNum Then
                MaxNum= MaxNum + DeltaDim
                ReDim Preserve x(1 To MaxNum), y(1 To MaxNum)
                End If
            End If
'In this example, lines are read that contain x
'and y coordinate values separated by tabs
            k=InStr(TxtLin,vbTab)
            x(nl)=Val(Left(TxtLin,k-1))
            y(nl)=Val(Mid(TxtLin,k+1))
        Wend
    Close #ff
'Release unused array space by keeping only
'the actual values just read from the file
    ReDim Preserve x(1 To nl), y(1 To nl)
End Sub