Stack

BET_StackItem class

Public Value As Variant 
Public NextItem As Variant 

Private Sub Class_Initialize() 
   Set NextItem = Nothing 
End Sub 

Private Sub Class_Terminate() 
   Set NextItem = Nothing 
End Sub 

BET_Stack class

Private _stackTop As BET_StackItem 

Public Function Method_Pop() As Variant 
   If (Property_StackEmpty = False) Then 
      Method_Pop = _stackTop.NextItem 
      Set _stackTop = _stackTop.NextItem 
   End If 
End Sub 

Public Sub Method_Push(ByVal vText As Variant) 
Dim newTop As BET_StackItem 
   Set _newTop = New BET_StackItem 
   newTop.Value = vText 
   Set _newTop.NextItem = _stackTop 
   Set _stackTop = newTop 
End Sub 

Public Function Method_Peek() As Variant 
   If (Property_StackEmpty = True) Then 
      Method_Peek = Null 
   Else 
      Method_Peek = _stackTop.Value 
   End If 
End Function 

Public Property Get Property_StackEmpty() As Boolean 
   Property_StackEmpty = (_stackTop Is Nothing) 
End Property 

Private Sub Class_Initialize() 
   Set _topStack = Nothing 
End Sub 

Private Sub Class_Terminate() 
   Set _topStack = Nothing 
End Sub 

Sample

Dim myStack As BET_Stack 
Dim myStackItem As BET_StackItem 
   myStack = New BET_Stack 

   myStackItem = New BET_StackItem 
   myStackItem.Value = 5 
   myStack.Method_Push myStackItem 

   myStackItem = New BET_StackItem 
   myStackItem.Value = 10 
   myStack.Method_Push myStackItem 

   Debug.Print myStack.Method_Pop() 
   Debug.Print myStack.Method_Pop() 

System.Collections.Stack

This does not work with Office 365.
This only works if you have .NET 3.5 installed.
Add a reference to C:\Windows\Microsoft.NET\Framework\v4.0.30319\mscorlib.dll for early binding.

Public Sub CreateStack() 
Dim oStack As Object 
Set oStack = CreateObject("System.Collections.Stack") 
 
oStack.Push "Monday" 
oStack.Clear 

oStack.Push "Tuesday" 
oStack.Push "Wednesday" 
oStack.Push "Thursday" 
oStack.Push "Friday" 
 
Debug.Print oStack.Peek() 

If (oStack.Contains("Monday") = True) Then 
   Debug.Print "Monday was removed" 
End If 

Debug.Print "Last day added was : " & oStack.Pop() 
 
Set oStack = Nothing 
End Sub