[RESOLVED] Fastest way to save/load variant array to/from file

[Ellis Dee]

A have a variant array that could be one or two dimensions, could hold any data type, and I want to be able to save it to a file and read it back in from that file as quickly as possible.

What's the absolute fastest way to do this? I don't much care what the actual file format ends up being. (Text, binary, whatever.)

[randem]

Binary is the fastest way. In that way it states the same as it was in memory. So you would need to use arrays then write the whole array at once.

[Ellis Dee]

That sounds ideal. Could you start me off with a code snippet? Doesn't have to be anything fancy.

[randem]

What kind of structure are you attempting to write to file? Post an example to work with.

[Mr.Mac]

In QBasic, I would recommend BSAVE/BLOAD, but I see those commands are not in VB.

Mac

[Ellis Dee]

What kind of structure are you attempting to write to file? Post an example to work with.

The structure is variable. Here's some examples:

Sub Main()
    Dim varArray As Variant
    Dim lngArray() As Long
    Dim strFile As String
    Dim i As Long

    strFile = App.Path & "\Array"

    ' Two-dimensional
    ReDim varArray(1,1)
    varArray(0,0) = 1
    varArray(0,1) = "Hello"
    varArray(1,0) = 2
    varArray(1,1) = ", World!"
    SaveArrayToFile varArray, strFile
    Erase varArray
    LoadArrayFromFile varArray, strFile
    Debug.Print varArray(0,1) & varArray(1,1)
    Erase varArray
    
    ' Single-dimension Date
    ReDim varArray(10)
    For i = 0 To 10
        varArray(i) = DateAdd("d", i, Now())
    Next
    SaveArrayToFile varArray, strFile
    Erase varArray
    LoadArrayFromFile varArray, strFile
    Debug.Print "3 days from now is " & varArray(3)
    Erase varArray
    
    ' Typed single-dimension Long
    ReDim lngArray(10)
    For i = 0 To 10
        lngArray(i) = 7 * i
    Next
    SaveArrayToFile lngArray, strFile
    Erase lngArray
    LoadArrayFromFile lngArray, strFile
    Debug.Print "7 * 9 = " & lngArray(9)
    Erase lngArray

    ' Single-dimension string
    ReDim varArray(1)
    varArray(0) = "Hello,"
    varArray(1) = " World!"
    SaveArrayToFile varArray, strFile
    Erase varArray
    LoadArrayFromFile varArray, strFile
    Debug.Print varArray(0) & varArray(1)
    Erase varArray
End Sub

Public Sub SaveArrayToFile(pvarArray As Variant, pstrFile As String)
    Dim strFile As String
    Dim strHeader As String 

    strFile = pstrFile & ".dat"
    strHeader = pstrFile & ".hdr"

    ???
End Sub

Public Sub LoadArrayFromFile(pvarArray As Variant, pstrFile As String)
    Dim strFile As String
    Dim strHeader As String 

    strFile = pstrFile & ".dat"
    strHeader = pstrFile & ".hdr"

    ???
End Sub

No need to worry about validating that the passed array is in fact an array; I can handle all the validation. Also, if saving the structure information to the same file is just as fast, no need to split it off to a second file.

So the arrays will hold any native data type (no UDTs or objects) and be either 1- or 2-dimensional. The passed arrays may be originally declared either as a typed array or simply as a Variant.

[Ellis Dee]

This function may be of help:

' Returns 0 for unintialized array, -1 for non-array
Public Function ArrayDimensions(pvarArray As Variant) As Long
    Dim lngTemp As Long
    Dim i As Long
    
    On Error Resume Next
    Do
        i = i + 1
        lngTemp = UBound(pvarArray, i)
        Select Case Err.Number
            Case 13: ArrayDimensions = -1
            Case 9: ArrayDimensions = i - 1
        End Select
    Loop Until Err.Number
End Function

[Ellis Dee]

I'm hurtin' for a solution on this one. Does nobody have any ideas?

Even if it's not all-purpose, I would appreciate any kind of approach. How about we start off with just a single-dimension variant array holding Longs.

Anyone?

[randem]

Could you repost your code in post #6 or replace those vbcode tags with just the code tags. Those numbers are annoying to get rid of in a copy/paste. I will implement something.

[Ellis Dee]

No problem, sorry about that.

[randem]

Here ya go... Enjoy.

[Ellis Dee]

Aw yeah, now that is what I'm talking about.

Thanks much, randem. It's as simple as simple gets. You rock.