Question problem in check if a member of a structure is nothing

[pooya1072]

hi
i create a structure like this :

Public Structure EquationColumns
   Dim ColumnName As String
End Structure

Public Structure EquationsInfo
   Dim SourceName As String
   Dim EquationColumn() As EquationColumns
   Public Sub x(ByVal Index As Integer)
      If EquationColumn(Index) [COLOR=#FF0000]IsNot [/COLOR][COLOR=#000000]Nothing [/COLOR]Then MsgBox "Message"
   End Sub
End Structure

an error occured when i write "IsNot" Or "Is" Or "=" Or "<>" between "EquationColumn(Index)" And "Nothing" .
for IsNot Error is :
'IsNot' requires operands that have reference types, but this operand has the value type

for "<>" Error is :
Operator '<>' is not defined for types

 

[JohnH]

Change both your types to Class instead of Structure. Structures are used to represent values, and classes represent objects.
Choosing Between Classes and Structures
Structures and Classes (Visual Basic)
Value Types and Reference Types