Find specific cells, change value of adjacent cell, value depends on location (Excel for Mac, 15.6) - vba

Question

this is my first post here, I know I'm articulating this poorly.
I'm trying to find cells containing a specific phrase in a column of dates. This phrase marks the beginning of a section. I then want to state the number of days elapsed from the first date in each section to other dates in the section. The values returned should show up in the adjacent column. Below is an example of the columns.
Dates and Elapsed number of days in adjacent column
I use this formula in the 2nd column:
=A15-$A$15
And then drag this down to cells in the relevant section. I'm trying to automate this process.
I found this code on this site and changed it a little bit to get this:
For Each cCell In Range("A1,A900")
cCell.Select
If ActiveCell.Value = "Phrase" Then
ActiveCell.Offset(1, 1).Value = "-"
End If
Next cCell
So my struggle is what to say in the 2nd Value field. I somehow need to get each section to subtract the first date of each section (the date right under "Phrase").
Another challenge is to copy that first adjacent cell that was changed, and then paste special into the cells below, but stopping once the next "Phrase" appears.
I'll elaborate any way I can. Thanks.

Answer 1

I think it's fair to say your question doesn't show much effort at solving this problem and the code snippet simply places a dash next to a "Phrase" cell. However, for a wider audience the question is interesting because it highlights the difference between automating an Excel keystroke task and writing code to process data which is then written in an Excel worksheet. Both use VBA but the former is simply a programmatic record of keystrokes and the latter is an algorithmic solution.
The telling phrase in your question is: I use this formula in the 2nd column ... and then drag this down to cells in the relevant section. I'm trying to automate this process. It would be possible to do this by using VBA to reproduce a bunch of worksheet functions but it's fiddly and could become complicated. I'll leave someone else to answer that as they'd need to spend more time on the answer than you have on the question (one of my don't do rules!).
If, on the other hand, you step away from trying to automate keystrokes and towards VBA for data processing, the problem becomes very trivial. It's a really good example of how VBA, in just a few lines, can solve problems that Excel functions might take pages to do, and probably not reliably.
So here's the code as a VBA solution. It'll need some data checking lines added to deal with blank cells, non-dates, etc. but I'll hand that task back to you:
Dim ws As Worksheet
Dim firstCell As Range
Dim lastCell As Range
Dim dataCells As Range
Dim v As Variant
Dim output() As Variant
Dim r As Long
Dim refDate As Long
'Define the range to be worked
Set ws = ThisWorkbook.Worksheets("Sheet1") 'amend as required
Set firstCell = ws.Range("A1") 'amend as required
Set lastCell = ws.Cells(ws.Rows.Count, "A").End(xlUp) 'amend as required
Set dataCells = ws.Range(firstCell, lastCell)
'Read the values and size the output array
v = dataCells.Value2 'use Value2 to avoid date format issues
ReDim output(1 To UBound(v, 1), 1 To 1)
'Loop through the values, resetting the reference date on each "Phrase"
For r = 1 To UBound(v, 1)
If v(r, 1) = "Phrase" Then
output(r, 1) = "-"
refDate = v(r + 1, 1)
Else
output(r, 1) = v(r, 1) - refDate
End If
Next
'Write output into next column
dataCells.Offset(, 1).Value = output