Simple Excel VBA takes ages - excel

Question

I have written a simple VBA script (code below) that should inspect every cell in a certain column. Here I want to do some string manipulation ( i wante to search for "." in the string and then take the right side, but because I could not get it to work I always take the 4 digit as a start). I then copy the manipulated string into another cell and later back. The code works, but for some reason, it takes ages to run on only 35 cells!
I´m still a kook on VBA and wanted to get input what could be the reason for it and what I could improve to get a faster runtime. Is it because I take all strings froms 4 up to 50 ?
Sub EditStatus()
Application.DisplayAlerts = False
ActiveSheet.Name = "Backend"
myNum = Application.InputBox("Please enter the row number until which you would like to update the status column (only for new entries)")
For i = 2 To myNum
Cells(i, 20).Value = Mid(Cells(i, 10), 4, 50)
Cells(i, 10).Value = Cells(i, 20).Value
Next i
Range("T1:T200").Clear
Application.DisplayAlerts = True
End Sub
Thanks

Answer 1

No need for a loop. You can enter the formula in the entire range in 1 go and then convert them to values before putting the values back in Col J
Replace
For i = 2 To myNum
Cells(i, 20).Value = Mid(Cells(i, 10), 4, 50)
Cells(i, 10).Value = Cells(i, 20).Value
Next i
With
With Range("T2:T" & myNum)
.Formula = "=MID(J2, 4, 50)"
.Value = .Value
Range("J2:J" & myNum).Value = .Value
End With
Alternatively, you can directly perform the same action in Col J without the helper column T. For example you can do all that in 1 line as explained HERE as well
Simply replace
For i = 2 To myNum
Cells(i, 20).Value = Mid(Cells(i, 10), 4, 50)
Cells(i, 10).Value = Cells(i, 20).Value
Next i
Range("T1:T200").Clear
with
Range("J2:J" & myNum).Value = Evaluate("Index(MID(" & "J2:J" & myNum & ", 4, 50),)")

Answer 2

Replace Values In-Place
Adjust the values in the constants section.
This solution overwrites the data and doesn't use a helper column, but you can test it with one indicated near the end of the code.
Solve the renaming (Backend) part as needed.
The Code
Option Explicit
Sub EditStatus()
' Define constants.
Const sPrompt As String = "Please enter the row number until which you " _
& "would like to update the status column (only for new entries)"
Const sTitle As String = "Enter Number"
Const wsName As String = "Backend"
Const First As Long = 2
Const cCol As Long = 10 ' J
Const Delim As String = "."
' Define workbook.
Dim wb As Workbook: Set wb = ThisWorkbook ' Workbook containing this code.
' Require input.
Dim Last As Variant
Last = Application.InputBox( _
Prompt:=sPrompt, Title:=sTitle, Default:=First, Type:=1)
' Validate input.
If VarType(Last) = vbBoolean Then
MsgBox "You cancelled."
Exit Sub
End If
If Last < First Then
MsgBox "Enter a number greater than " & First - 1 & "."
Exit Sub
End If
If Int(Last) <> Last Then
MsgBox "Enter a WHOLE number greater than " & First - 1 & "."
Exit Sub
End If
' Define column range.
Dim rg As Range
Set rg = wb.Worksheets(wsName).Cells(First, cCol).Resize(Last - First + 1)
' Write values from column range to array.
Dim Data As Variant
If rg.Rows.Count > 1 Then
Data = rg.Value
Else
ReDim Data(1 To 1, 1 To 1): Data = rg.Value
End If
' Declare additional variables
Dim cValue As Variant ' Current Value
Dim i As Long ' Current Row (Array Row Counter)
Dim fPos As Long ' Current Delimiter Position
' Replace strings containing the delimiter, with the sub string
' to the right of it.
For i = 1 To UBound(Data)
cValue = Data(i, 1)
If Not IsError(cValue) Then
fPos = InStr(1, cValue, Delim)
If fPos > 0 Then
Data(i, 1) = Right(cValue, Len(cValue) - fPos)
End If
End If
Next i
' Maybe rather test with the following (writes to column 20 ("T")).
'rg.Offset(, 10).Value = Data
' Write values from array to column range.
rg.Value = Data
End Sub