Using data from another workbook (other than the active one) - excel

Question

Ignoring what my code actually does (it's not important to my question):
I want to be able to open my excel file, press a button, have the code use data in that workbook and another opened workbook (so I would have two workbooks opened at the same time, the macro runs in one of them but can take data from both of them).
The trick here is that I can't seem to find code to access the other workbook that I've opened up, so I can only take info from the active workbook.
For example,
Private Function GetLastRow() As Integer
Dim myLastRow As Integer
Set ws = ThisWorkbook.Sheets("Sheet1")
myLastRow = Range("C" & Rows.count).End(xlUp).Row
GetLastRow = myLastRow
End Function
This code lets me access the active workbook (the one running the code), using ThisWorkbook.
Is there another function capable of allowing me to access another opened workbook?

Answer 1

You could change your function to be more flexible.
Private Function GetLastRow(InWorksheet As Worksheet, InColumn As Variant) As Long
GetLastRow = InWorksheet.Cells(InWorksheet.Rows.Count, InColumn).End(xlUp).Row
End Function
So you can call it …
Sub Test()
Dim LastRow As Long
LastRow = GetLastRow(ThisWorkbook.Worksheet("Sheet1"), "C") 'column as letter
'or
'LastRow = GetLastRow(ThisWorkbook.Worksheet("Sheet1"), 3) 'column as number
End Sub
So you can even run this on another workbook using:
LastRow = GetLastRow(Workbooks("OtherWorkbook.xlsx").Worksheet("Sheet1"), "C") 'column as letter

Answer 2

There is a Workbook object built into VBA that you can use. This documentation should give you the information that you need https://learn.microsoft.com/en-us/office/vba/api/excel.workbook
You would simply put the name of your other workbook in quotes, in parentheses after using the Workbook object (see example on page I hyperlinked). Good luck!

Answer 3

I guess this is what you looking for.
When you have more then one Workbook active you can switch between then.
Sub GetLastRow()
Dim myLastRow As Integer
'Active Workbook
Set ws = ThisWorkbook.Sheets("Plan1")
myLastRow = ws.Range("C" & Rows.Count).End(xlUp).Row
MsgBox myLastRow
'Way when you know workbook name
Workbooks.Open Filename:=ActiveWorkbook.Path & "\Teste1.xlsx"
Set ws1 = Application.Workbooks("Teste1.xlsx").Sheets("Plan1")
myLastRow1 = ws1.Range("C" & Rows.Count).End(xlUp).Row
MsgBox myLastRow1
Dim myLastRow As Integer
'If you don't know the name but, opened after your main Workbook
Set ws3 = Application.Workbooks(2).Sheets("Plan1")
myLastRow3 = ws1.Range("C" & Rows.Count).End(xlUp).Row
MsgBox myLastRow3
End Sub