Visual Basic

Public Structure InnerStruct
    Public InnerTest As String
End Structure
Public Structure RootStruct
    Public Test As String
    Public myStruct As InnerStruct
End Structure

Public Class Form1

    Public Sub ShowInnerText(ByVal whatStruct As RootStruct)
        MessageBox.Show(whatStruct.myStruct.InnerTest)
    End Sub

    Private Sub Button1_Click(ByVal sender As System.Object, _
      ByVal e As System.EventArgs) Handles Button1.Click

        Dim newStruct As RootStruct
        newStruct.myStruct.InnerTest = "Hello world"
        ShowInnerText(newStruct)

    End Sub

End Class

I are troll

Public Structure InnerStruct
    Public InnerTest As String

    Public Sub Init
        InnerTest = "initialize your vars here"
    End Sub
End Structure
Public Structure RootStruct
    Public Test As String
    Public myStruct As InnerStruct
End Structure

Public Structure RootStruct
    Public Test As String
    Public myStruct As InnerStruct

    Public Structure InnerStruct
        Public InnerTest As String
    End Structure
End Structure

I are troll