Dynamically reading structure fields

  • Thread starter Thread starter sameerishah
  • Start date Start date
S

sameerishah

Hi,

I have a need to read the fields of a structure in a for loop.
for eg. the structure looks like:
str.a1, str.a2, str.a3 where a1, a2, a3 are of type string
How do I do it?

Thanks in advance,
Sam
 
Private Structure mystruct
Public field1 As Short
Public field2 As String
Public pairForListItem As String
End Structure

Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles MyBase.Load
Dim myarraylist As New ArrayList
Dim InstanceofMyClass As mystruct
Dim i As Integer
For i = 0 To 5
With InstanceofMyClass
.field1 = i
.field2 = "field 2 value " & i
.pairForListItem = "value " & i & "Text " & i
End With
myarraylist.Add(InstanceofMyClass)
Next
End Sub
 
Hi,

Thanks for taking the time out to help me.

In your code, it seems like you are assigning values to the fields of
the structure and what I need is a way to read the fields values in a
For loop. Do you think that is doable?

Sam
 
I have a need to read the fields of a structure in a for loop.
for eg. the structure looks like:
str.a1, str.a2, str.a3 where a1, a2, a3 are of type string
Click to expand...

You should be able to do this with reflection. Below is a quick demo of how
to pull fields from a structure.

Module Module1

Sub Main()

Dim StructInstance As MyStruct
StructInstance.Prop1 = "Foo"
StructInstance.Prop2 = "Bar"

Dim propInfo As Reflection.FieldInfo() = Type.GetType("ConsoleApplication1.MyStruct").GetFields
For Each item As Reflection.FieldInfo In propInfo
Console.WriteLine(item.GetValue(StructInstance))
Next
Console.ReadKey()
End Sub

End Module

Public Structure MyStruct
Public Prop1 As String
Public Prop2 As String
End Structure

Be aware that there is a boxing penalty with structures and you may want
to use classes instead. You should read up on boxing and the performance
penalties they incur. You will be able to do the same kind of reflection
code with classes if you decide to change to that route.

Jim Wooley
http://devauthority.com/blogs/jwooley
 
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