Assuming that the last 'As ...' applies to all the variables on the line is a carry over from other languages

Each Dim variable needs a 'As <something>' otherwise it's Variant

inputArray is a Variant containing an array of Variants

rngInput is a Variant containing an Object of type Range


Capture.JPG



Look this over

Option Explicit

Sub DataConversion_1()
     
    Dim rngInput As Range, rngOutput As Range   '<<<<<<<<<<<<<<<<<<<<<<<
    Dim LastInputRow As Long, LastInputColumn As Long, i As Long, j As Long, counter As Long
    Dim arrayInput As Variant    '<<<<<<<<<<<<<<<<<<<<<<<<<
     
    MsgBox VarType(rngInput)
     
    With Sheets("Copy of Source Data")
         
        LastInputRow = .Cells(.Rows.Count, "A").End(xlUp).Row
        LastInputColumn = .Cells(1, .Columns.Count).End(xlToLeft).Column
        Set rngInput = .Range(.Cells(1, 1), .Cells(LastInputRow, LastInputColumn))
        arrayInput = rngInput
    
        MsgBox IsObject(rngInput)
        MsgBox IsObject(arrayInput)
        MsgBox IsArray(arrayInput)
    
        For i = LBound(arrayInput, 1) To UBound(arrayInput, 1)
            For j = LBound(arrayInput, 2) To UBound(arrayInput, 2)
                MsgBox i & " --- " & j
            Next j
        Next I
    
    
    End With
End Sub