Question

I’m using a loop condition to check if there is null value in the columns, then remove it.

-Original author

[STart:]
    For i As Integer = counter To dt1.Columns.Count - 1
      For x As Integer = 0 To dt1.Rows.Count - 1
        if some condition then
            something = true
        else
                something = false
            counter = counter + 1
                Goto [Start]
        end if
      Next
    
      If something = true
        dt1.Columns.Remove(dt1.Columns(i))
        i -= 1
      End If
    Next
  End If

Sometimes it runs correctly and sometimes even though when i becomes greater than (dt.columns.count - 1), it still executes the for loop and throws an error that there is no column with that index. I must be missing something here but I’m not able to debug the issue.

Do you guys find anything wrong with this code?

Answer 1

The statement dt1.Columns.Count is evaluated at the very beginning of the for loop. It does not get re-evaluated each time the loop runs.

So when you remove a column in the body of the loop it causes the end condition of the loop to go wrong.