Question

I have a List of structure’s in my VB.NET program, and I’m looping over them, and change the values of the objects in the list, as follows

Dim retvals As List(Of SomeStruct) = parser.RetrieveData(new_path)

 For i As Integer = 0 To retvals.Count - 1 Step 1
 dim temp as SomeStruct = retvals(i)

  temp.A = GetValueForA()
  temp.B = GetValueForB() 

 Next

When I look into my List of structs after this loop, none of the values were overwritten. Why? I thought that I had references in my list, so if I change reference A to a struct, then reference B to the same struct should see the changes?

What am I missing?

Answer 1

I realized what the problem was, the Structure in .NET is a value type, meaning the contents will get copied into the List. So changing the temp variable will not change the original in the List

I fixed it by using a class instead, which is a reference type.