Selecting variable by name - vb.net

Question

I'm not sure of the appropriate search term so please close and point me to a duplicate if that's the case.
I have a structure with has multiple variables. I've created an array of the type of the structure. I've added data to a few indexes of the array. I now want to select the a specific variable based on the name of the variable.
He's an example of the structure:
structure struc
dim name as string
dim lvl as integer
dim capacity as integer
end structure
And the deceleration of the array:
dim vills(3) as struc

Answer 1

You should be using public fields, not variables Actually you have the terminology correct according to MSDN, the only thing you are missing is the access modifier i.e.
Public Structure Struc
Public Name As String
Public Lvl As Integer
Public Capacity As Integer
End Structure
At the moment your variables are private which means they aren't accessible from outside your Structure.
Looking at your comments it looks like you are trying to access the property by name dynamically rather than knowing it at compile time. There are a few ways of doing this, most of which involve some Reflection.
You should perhaps have a look at ExpandObject - it's effectively a key/value dictionary with the characteristics of a normal class-type object so you get the best of both worlds e.g.
Dim struct As Object = New ExpandoObject()
struct.name = "SomeValue"
struct.lvl = 3
struct.capacity = 100
Console.WriteLine(struct["name"])
Console.WriteLine(struct["lvl"])

Answer 2

As Tony Hopkinson mentioned, it is possible via Reflection:
Public Class Form1
Structure struc
Dim name As String
Dim lvl As Integer
Dim capacity As Integer
End Structure
Dim vills(3) As struc
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
For i As Integer = 0 To vills.Length - 1
vills(i).lvl = i * 10
Next
End Sub
Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click
Dim fi As Reflection.FieldInfo
Dim fieldName As String = "lvl"
For i As Integer = 0 To vills.Length - 1
fi = vills(i).GetType.GetField(fieldName, Reflection.BindingFlags.Instance Or Reflection.BindingFlags.NonPublic Or Reflection.BindingFlags.Public)
If Not IsNothing(fi) Then
Dim value As Object = fi.GetValue(vills(i))
Debug.Print(i & ": " & value.ToString)
End If
Next
End Sub
End Class
Up to you to decide if it's worth it...

Answer 3

I really think that if this is an important and frequent requirement (find an element by key) then you should think twice and change your array to a Dictionary(Of string, struc) and use something like this
Dim vills = new Dictionary(of String, struc)
Dim s = new struc()
s.name="k1"
s.lvl=1
s.capacity=1
z.Add(s.name, s)
....
struc c = vills("k1")
if(c IsNot Nothing) Then
Console.WriteLine(c.lvl.ToString())
End If
but if you still want to use an array you could search your struc array by name using Linq
Structure struc
Public Dim name as string
Public Dim lvl as integer
Public Dim capacity as integer
End Structure
Sub Main
Dim vills(3) as struc
....
Dim c as struc = wills.Where(Function(x) (x.name="keyName")).Single()
if(c.name IsNot Nothing) then
Console.WriteLine("Found")
End If
End Sub