Question

I’ve always use String.IsNullOrEmpty to check for a empty string. It recently come to my attention that a ‘ ‘ count as not a empty string. For example,

 Dim test As String = ' '     If String.IsNullOrEmpty(test) Then         MessageBox.Show('Empty String')     Else         MessageBox.Show('Not Emtpy String')     End If 

It will show ‘Not Empty String’. So how do we check for ‘ ‘ or ‘ ‘ in a string?

edit: I wasn’t aware that ‘ ‘ count as character.

Answer 1

Try this method to check for blank strings. It is different from the Trim() versions in that it does not allocate a new string. It also uses a more expanded notion of whitespace.

Public Function IsNullOrBlank(ByVal str as String) As Boolean   if String.IsNullOrEmpty(str) Then     Return True   End IF   For Each c In str     IF Not Char.IsWhiteSpace(c) Then       Return False     End If   Next   Return True End Function