Speeding Up VB.NET application to Excel - arrays

Question

I have written a VB.NET application in Visual Studio 2015. (first time ever had any contact with visual basic or VS). The application takes an input csv file, analyses it and splits it according to that analysis into 2 output csv files. For one of these output files, I then need to change every blank cell to have the value of zero. My prob, is that the code i've made is processing 750 input csv files to produce 1500 output files and each process in the loop is taking 5 mins meaning it's taking up to 5 days to run!! That is too long!
I'm trying to work out how to make the code run quicker. One easy first step would be in the blank cell to zero operation as i'm currently doing it cell by cell. I read that better to do via an array but i'm unsure how to code it...Can someone help?
My code now is:
Dim forceDataRangeDest, cell As Excel.Range
Dim blank As String
Dim forceDataRow, lastDataRow As Integer
'copy force data from original workbook to sheet 1 of new workbook
If ws.Range("Z" & (forceLegRowStart + 1)).Value = "Force Plate 3" Then
forceDataRow = forceDataRow + 2
forceDataRangeSrc = ws.Range("Z" & forceDataRow & ":AK" & lastDataRow)
Else forceDataRangeSrc = ws.Range("A" & forceDataRow & ":M" & lastDataRow)
End If
wsData = wbForce.Sheets("Sheet1")
wsData.Name = "Data"
forceDataRangeDest = wsData.Range("A1")
forceDataRangeSrc.Copy(forceDataRangeDest)
'insert new column A if Force Plate 3 data is one taken for the time interval data of column A
If ws.Range("Z" & (forceLegRowStart + 1)).Value = "Force Plate 3" Then
wsData.Columns("A:A").Insert(1)
'write in the Data
forceDataRangeSrc = ws.Range("A" & forceDataRow & ":A" & lastDataRow)
forceDataRangeSrc.Copy(wsData.Range("A1"))
End If
forceDataRangeDest = wsData.Range("A1:M" & ((lastDataRow - forceDataRow) + 1))
For Each cell In forceDataRangeDest
blank = cell.Value
If String.IsNullOrWhiteSpace(blank) Then
cell.Value = 0
End If
Next
It is the For Each cell at the bottom of this sample code that i think is really increasing the process time...how would i write that as an array and then write array into excel in one go?
Many thanks for any help you can give.

Answer 1

You could use the Range.Find and Range.FindNext methods in VBA which would be quicker than looping through all the cells. Here's an example of the VBA code:
Sub FindEmptyCells()
Dim found As Range
Dim firstCell As String
Set found = ActiveSheet.UsedRange.Find(What:="", LookAt:=xlWhole)
firstCell = found.Address
Do While Not (found Is Nothing)
Debug.Print found.Address
Set found = ActiveSheet.UsedRange.FindNext(found)
If found.Address = firstCell Then
Exit Do
End If
Loop
End Sub
EDIT: Added the code to use OP's range object
Dim found As Range
Dim firstCell As String
Set found = forceDataRangeDest.Find(What:="", LookAt:=xlWhole)
firstCell = found.Address
Do While Not (found Is Nothing)
found.Value = 0
Set found = forceDataRangeDest.FindNext(found)
If found.Address = firstCell Then
Exit Do
End If
Loop