VBA stop processing at first empty row - vba

Question

I have vba that produces a flat text file of the selected column.
The issue is that the process takes a while because usually the column letter is clicked and the whole column is highlighted including all the unused cells.
How can i get the macro to stop processing when it finds the first empty row?
Here is my code.
Sub testlist()
Open "C:\Users\gaum\Desktop\Work\NCL\testlist.lst" For Output As #1
For NR = 1 To Selection.Rows.Count
For NC = 1 To Selection.Columns.Count
ExpData = Selection.Cells(NR, NC).Value
If IsNumeric(ExpData) Then ExpData = Val(ExpData)
If IsEmpty(Selection.Cells(NR, NC)) Then ExpData = ""
If NC <> NumCols Then
If Not ExpData = "FilePath" Then Print #1, ExpData
End If
Next NC
Next NR
Close #1
End Sub
Also am i able to get the macro to produce the output if i have multiple selections i.e ctrl and left click various cells, it currently only outputs the first highlight.
Many Thanks

Answer 1

Since you asked 2 separate questions, I will address them both separately.
The easiest way to stop processing when you encounter a blank row is to add a check before your 2nd For..Next loop. The issue is how to check. The simplest way to check if an entire range is empty is to use the CountA worksheet function.
If WorksheetFunction.CountA(Range(NR & ":" & NR).EntireRow) = 0 Then Exit For
The above will basically use the worksheet function CountA and count the number of cells within the range that are not blank (using CountA is important here as the Count worksheet function will only count numeric cells and not non-numeric ones, whereas CountA will count anything except blanks. The other advantage you get by using the WorksheetFunction object is you can adjust the Range object as you need if you only want to check a few columns and the not the entire row by just specifying the specific Range and not using .EntireRow.
The next question is how to deal with multiple selected ranges. There is another member of the Selection class called Areas, which should given you the functionality you need. Areas is a collection that has the ranges for each individual selection range you make.
You can reference each selection range independently by using the 1-based index of the selection:
NumAreaRows = Selection.Areas(1).Rows.Count 'gets the number of rows in the first selected range
NumAreaCols = Selection.Areas(2).Columns.Count 'gets the number of columns in the second selected range
So you could put both all together into your solution:
Sub testlist()
Open "C:\Users\gaum\Desktop\Work\NCL\testlist.lst" For Output As #1
For NA = 1 To Selection.Areas.Count
For NR = 1 To Selection.Areas(NA).Rows.Count
If WorksheetFunction.CountA(Range(NR & ":" & NR).EntireRow) = 0 Then Exit For
For NC = 1 To Selection.Areas(NA).Columns.Count
ExpData = Selection.Areas(NA).Cells(NR, NC).Value
If IsNumeric(ExpData) Then ExpData = Val(ExpData)
If IsEmpty(Selection.Areas(NA).Cells(NR, NC)) Then ExpData = ""
If NC <> NumCols Then
If Not ExpData = "FilePath" Then Print #1, ExpData
End If
Next NC
Next NR
Next NA
Close #1
End Sub
The placement of the CountA function and the Exit For statement here allows you to loop through each selected range independently and it won't exit completely if you have a blank row in one of the ranges.

Answer 2

Given this process takes a while, you would be better off going beyond stopping at a blank cell, and removing the inefficient range loop altogether. The code below
Uses a variant array rather than range
removes the redundant two-step IF test (if ExpData is numeric it cannot also be "FilePath")
code
Sub testlist()
Dim X
Dim lngCnt As Long
X = Selection
If IsEmpty(X) Then Exit Sub
Open "C:\Users\gaum\Desktop\Work\NCL\testlist.lst" For Output As #1
For lngCnt = 1 To UBound(X)
If Len(X(lngCnt, 1)) = 0 Then Exit For
If IsNumeric(X(lngCnt, 1)) Then Print #1, Val(X(lngCnt, 1))
Next
Close #1
End Sub