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Expression is a value and therefore cannot be the target of an assignment  vb.net

Posted on 2010-08-18
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Last Modified: 2013-11-27
Public Structure _cache
    Public loading As Boolean
End Structure


Public Class Server
    Public _cache_List As New List(Of _cache)()
...

For index As Int16 = 0 To _cache_List.Count - 1
_cache_List(index).loading = false '--> error
Next

"Expression is a value and therefore cannot be the target of an assignment "

what was wrong in the code above?
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Question by:JSW21
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4 Comments
 
LVL 52

Expert Comment

by:Carl Tawn
ID: 33469523
The problem is that you are making an indirect reference to a Value-type (your structure) which results in it being classed as an expression.
You will have to declare a variable to hold a direct reference to the item and assign through that:


For index As Int16 = 0 To _cache_List.Count - 1
   Dim item As _cache = _cache_list(index)
   item.loading = false
Next

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Author Comment

by:JSW21
ID: 33471957
Hi there
So I change the Structure into Class and it works.
I didnt know using structure will have different from class.

Do you think i am doing the right thing.
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LVL 52

Accepted Solution

by:
Carl Tawn earned 500 total points
ID: 33472597
Structures are fundamentally different from classes in that they are value-types rather than reference types. Whether or not you need a struct rather than a class depends largely on its intended use.
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Author Closing Comment

by:JSW21
ID: 33479653
I will need to use class as I need to modify its values.
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