Concatenate hyperlink in Powerpoint VBA - vba

Question

I am trying to concatenate a URL with many different parts(variables) added to the end of the URL.
I have a button and when you click the button it will takes you to the a specific site using the slide index of the current slide.
When the button is click I want it to go to "google.com/p" + Slide.Index + slide.ID + ActivePresentation.fileName
I know the syntax aren't correct but hopefully you get the GIST.
Currently I have this code:
Private Sub CommandButton21_Click()
Dim projId AS Integer = 617
Dim URL AS String = "www.google.com"
Dim coID = "m01"
Dim coTitle AS String = "New CC Project"
Dim oSl As Slide
Dim pgId
ActivePresentation.FollowHyperlink _
Address:="http://google.com/p" + oSl.SlideID
NewWindow:=True, AddHistory:=True
End Sub
Thanks in advance

Answer 1

This should get you a bit closer:
Private Sub CommandButton21_Click()
' You can't assign values to variables at the same time
' as you DIM them; you CAN do so with Constants:
Const projId As Integer = 617
Const URL As String = "www.google.com"
Const coID As String = "m01"
Const coTitle As String = "New CC Project"
Dim oSl As Slide
'Dim pgId
' You can't just refer to oSl; you have to first tell it WHICH slide
Set oSl = ActivePresentation.Slides(1) ' or whatever slide you want
ActivePresentation.FollowHyperlink _
Address:="http://google.com/p" & oSl.SlideID, _
NewWindow:=True, _
AddHistory:=True
End Sub

Answer 2

& is always evaluated in a string context, while + may not concatenate if one of the operands is no string:
Private Sub CommandButton21_Click()
Dim projId AS Integer
Dim URL AS String = "www.google.com"
Dim coID = "m01"
Dim coTitle AS String = "New CC Project"
Dim oSl As Slide
Dim pgId
projId = 617
ActivePresentation.FollowHyperlink _
Address="http://google.com/p" & oSl.SlideID
NewWindow=True
AddHistory=True
End Sub

Answer 3

I have fixed the issue, view the code below!
Sub CommandButton21_Click()
Dim sl As slide
Dim projId As Integer
Dim coID As String
Dim URL As String
Dim coTitle As String
Dim pgId
URL = "www.google.com"
projId = 617
coID = "m01"
coTitle = "New CC Project"
Set sl = SlideShowWindows(1).View.slide
ActivePresentation.FollowHyperlink _
Address:=URL & projId & "&coIdent=" & coID & "&coTitle=" & coTitle & "&pgIdent=" & sl.slideId & "&pgTitle=" & sl.slideId & "&pageFileName=" & ActivePresentation.FullName & "&pageOrder=" & sl.SlideIndex, _
NewWindow:=True, AddHistory:=True