VBA: copying the first empty cell in the same row - vba

Question

I am a new user of VBA and am trying to do the following (I got stuck towards the end):
I need to locate the first empty cell across every row from column C to P (3 to 16), take this value, and paste it in the column B of the same row.
What I try to do was:
Find non-empty cells in column C, copy those values into column B.
Then search for empty cells in column B, and try to copy the first non-empty cell in that row.
The first part worked out fine, but I am not too sure how to copy the first non-empty cell in the same row. I think if this can be done, I might not need the first step. Would appreciate any advice/help on this. There is the code:
Private Sub Test()
For j = 3 To 16
For i = 2 To 186313
If Not IsEmpty(Cells(i, j)) Then
Cells(i, j - 1) = Cells(i, j)
End If
sourceCol = 2
'column b has a value of 2
RowCount = Cells(Rows.Count, sourceCol).End(xlUp).Row
'for every row, find the first blank cell, copy the first not empty value in that row
For currentRow = 1 To RowCount
currentRowValue = Cells(currentRow, sourceCol).Value
If Not IsEmpty(Cells(i, 3)) Or Not IsEmpty(Cells(i, 4)) Or Not IsEmpty(Cells(i, 5)) Or Not IsEmpty(Cells(i, 6)) Then
Paste
~ got stuck here
Next i
Next j
End Sub

Answer 1

Your loop is really inefficient as it is iterating over millions of cells, most of which don't need looked at. (16-3)*(186313-2)=2,422,043.
I also don't recommend using xlUp or xlDown or xlCellTypeLastCell as these don't always return the results you expect as the meta-data for these cells are created when the file is saved, so any changes you make after the file is saved but before it is re-saved can give you the wrong cells. This can make debugging a nightmare. Instead, I recommend using the Find() method to find the last cell. This is fast and reliable.
Here is how I would probably do it. I'm looping over the minimum amount of cells I can here, which will speed things up.
You may also want to disable the screenupdating property of the application to speed things up and make the whole thing appear more seemless.
Lastly, if you're new to VBA it's good to get in the habit of disabling the enableevents property as well so if you currently have, or add in the future, any event listeners you will not trigger the procedures associated with them to run unnecessarily or even undesirably.
Option Explicit
Private Sub Test()
Dim LastUsed As Range
Dim PasteHere As Range
Dim i As Integer
Application.ScreenUpdating=False
Application.EnableEvents=False
With Range("B:B")
Set PasteHere = .Find("*", .Cells(1, 1), xlFormulas, xlPart, xlByRows, xlPrevious, False, False, False)
If PasteHere Is Nothing Then Set PasteHere = .Cells(1, 1) Else: Set PasteHere = PasteHere.Offset(1)
End With
For i = 3 To 16
Set LastUsed = Cells(1, i).EntireColumn.Find("*", Cells(1, i), xlFormulas, xlPart, xlByRows, xlPrevious, False, False, False)
If Not LastUsed Is Nothing Then
LastUsed.Copy Destination:=PasteHere
Set PasteHere = PasteHere.Offset(1)
End If
Set LastUsed = Nothing
Next
Application.ScreenUpdating=True
Application.EnableEvents=True
End Sub

Answer 2

Sub non_empty()
Dim lstrow As Long
Dim i As Long
Dim sht As Worksheet
Set sht = Worksheets("Sheet1")
lstrow = sht.Cells(sht.Rows.Count, "B").End(xlUp).Row
For i = 1 To lstrow
If IsEmpty(Range("B" & i)) Then
Range("B" & i).Value = Range("B" & i).End(xlToRight).Value
End If
Next i
End Sub