how to pass a variable from one sub to another?

Question

I am struggling to pass a srcFile variable from one sub to another. I would like to do the following:

1) load source file from my local path in loadFile() sub

2) Set srcFile as my source data workbook

3) I would like to call processWorkbook in my Main program so that it will take my srcFile, pass it to the Sub and do some actions on each worksheet of that file.

Apologies if I did not express myself clearly.

Sub Main()
  Call loadFile
  Call processWorkbook(srcFile)    
End Sub

' _____________________________________________________

Sub loadFile()
  Dim wrk As Worksheet
  Dim trg As Worksheet
  Dim Path As String
  Dim srcFile As Workbook

  Set wrk = Workbooks("Banks.xlsm").Sheets("Control")
  Set trg = Workbooks("Banks.xlsm").Sheets("Output")
  trg.Cells.ClearContents
  Path = wrk.Cells(1, 2).Value 'file path
  Set srcFile = Workbooks.Open(Path, ReadOnly:=False)
End Sub

' _____________________________________________________

Sub processWorkbook(wrk)
  Dim sht As Worksheet

  For Each sht In wrk.Sheets
    Call anotherSub
  Next sht
End Sub

Answer 1

The simplest way to do this is to declare a Workbook object in Sub Main and populate it from loadFile . There would be two ways this could be done: 1) Pass the Workbook object to loadFile by reference, or 2) Set the object from loadFile as an object.

I believe the second will be easier for you to understand, so I've used that to modify your code, as below.

Note that for this to work it was necessary to change loadFile to be a function, rather than a sub. (A function returns something.) Also, I removed the Call keyword from your code as this is no longer needed / used.

Sub Main()
   Dim srcFile As Workbook

   Set srcFile = loadFile
   processWorkbook srcFile 

End Sub

'_____________________________________________________

Function loadFile() as Workbook

  Dim wrk As Worksheet
  Dim trg As Worksheet
  Dim Path As String
  Dim srcFile As Workbook

  Set wrk = Workbooks("Banks.xlsm").Sheets("Control")
  Set trg = Workbooks("Banks.xlsm").Sheets("Output")
  trg.Cells.ClearContents
  Path = wrk.Cells(1, 2).Value 'file path
  Set srcFile = Workbooks.Open(Path, ReadOnly:=False)

  Set loadFile = srcFile
End Function

'_____________________________________________________

Sub processWorkbook(wrk)

Dim sht As Worksheet

For Each sht In wrk.Sheets
    Call anotherSub
Next sht

End Sub