VB learning notes

Hello everyone , I meet you again , I'm your friend, Quan Jun .

This month, due to the need of work , I learned a little VB.net operation Excel, Take notes

vb The subscript inside

vb There are three kinds of subscripts inside ：

• from 0 Start ： When we're in vb When defining an array in , Subscripts can only be from 0 Start
  • Dim arr(2) as String Medium arr The array length is 3 Notice that it's not 2
  • Dim arr(1 to 10) as String May be an error The lower bound of an array can only be 0
• from 1 Start ： Mainly used from 0 Exceptions will be thrown at first collections such as Tabs, Pages, Controls(listBox, TextBox),Excel The complex type subscripts are all from 1 Start
• Dictionary type Subscripts are key values

Try to use... In your code LBound and UBound To get the minimum and maximum subscripts of the array , It can be used in modules option base 1 To specify the subscript from 1 Start

VBA Detailed explanation of array subscript VBA option base Use

About Excel lastUsedRow and lastUsedColumn

Excel in Worksheet.UsedRange.Rows Refer to Excel The number of rows from the first non empty row to the last non empty row in the workbook R, So if there is a blank line in the workbook at the beginning , The final result returned is 「R – Number of empty lines at the beginning 」, So it may not be what we expected .

So don't rely on Worksheet.UsedRange.Rows To get the last line, you should use the reference link method

About getting Excel last rows

Why? vb Use in Worksheet.UsedRange.Rows.Count The result is wrong

About vb Exception handling

VB Use in try catch Capture exception , Use throw Throw an exception .

But if there are two classes in two modules , Want to be in A Class module B Class and capture B Exception of class function , Will give a warning ：Exception Type exception in 「 modular 2」 Occurs in but is not processed

#  modular  1
Public Class Test1
    Private T = new Class Test2

    Private Sub test1()
        Try
            T.Test()
        Catch ex as Exception
            MsgBox(ex.message)
        End Try
    End Sub

End Class

#  modular  2
Public Class Test2
    Public Sub Test()
        Throw new Exception(“error”)
    End Sub
End Class

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