Microsoft & .NET Visual Basic A Simple Stack Class

A Simple Stack Class

A Simple Stack Class


Author: Chris Eastwood
Author’s WebSite: http://www.eastwood60.freeserve.co.uk

This class module functions as a simple stack that can be dropped straight into any project requiring a stack object.

The class contains an internal collection of objects (variants) – you can simply change the data types passed in through the Push method and returned from the Pop method to use any data type you like.

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The Push / Pop functionality comes from using the internal Collections Add method with the underused ‘Before’ parameter set as 1.

Simply paste the code into a class module with a relevant name, eg. cStack and you can use it straight away in your projects :


option Explicit
'
' cStack.cls
'
' This class implements a simple stack structure - at the
' moment it only uses a variant item in the collection, but
' of course you can use any variable / object type you like !

'
' Our Internal Collection
'
private mStackCollection as Collection

private Sub Class_Initialize()
'
' Create the internal collection
'
set mStackCollection = new Collection
End Sub

private Sub Class_Terminate()
'
' Kill off the internal collection
'
set mStackCollection = nothing
End Sub

public Sub Push(byval vData as Variant)
'
' Push an item onto the stack
'

'
' If there's stuff already on the stack, then insert
' the new item before the first item
'
If mStackCollection.Count > 0 then
mStackCollection.Add vData, , 1
else
'
' Otherwise, just add it to the stack as the first item
'
mStackCollection.Add vData
End If
End Sub

public Function Pop() as Variant
'
' 'Pop' an item off the stack
'
If mStackCollection.Count > 0 then
If IsObject(mStackCollection.Item(1)) then
set Pop = mStackCollection.Item(1)
else
Pop = mStackCollection.Item(1)
End If
'
' Don't forget to remove the item from the stack
' once it's been popped !
'
mStackCollection.Remove 1
else
Err.Raise vbObjectError + 4999, "cStack::Pop", "Stack is empty"
End If

End Function

public property get StackCount() as Long
'
' Number of items in stack
'
StackCount = mStackCollection.Count
End property
'
'

Download Zipped Project File containing class and sample(5k)

Posted On: 7-Jan-2000

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