I, too, am just starting on C++ add-ins. I have Excel 2003 and MSFT C++
Express Beta. Is that enough to get the job done?

In terms of functionality, this might be available already in Excel. But, I
wrote it in vb anyway. ConnectTheDots returns a straight line across N
number of cells in the form of an array between start and end points. It
delivers a trend line; ignoring underlying midpoint values. The output array
(line) and input array (underlying data) are then displayed on a chart.

Function ConnectTheDots(aRng As Range)
'Assume range1 is a single column _
Or a single row _
If it is multi-dimensional, error _
If it is a single cell, return zero _
If either the first cell or last cell aren't numeric, error
Dim myTarg As Range, _
SrcList, Rslt(), _
i As Long, k As Long, step As Double
Application.Volatile
SrcList = aRng.Value
Set myTarg = Application.Caller

With myTarg
If .Areas.Count 1 Then
ConnectTheDots = _
"Function can be used only in a single contiguous range"
Exit Function '<<<<<
End If
If .Rows.Count 1 And .Columns.Count 1 Then
ConnectTheDots = _
"Selected cells must be in a single row or column"
Exit Function '<<<<<
End If
If .Cells.Count aRng.Cells.Count Then
ConnectTheDots = _
"Input and Output Ranges must be the same size"
Exit Function '<<<<<
End If
If .Cells.Count < aRng.Cells.Count Then
ConnectTheDots = _
"Input and Output Ranges must be the same size"
Exit Function '<<<<<
End If
ReDim Rslt(1 To IIf(.Rows.Count 1, .Rows.Count, .Columns.Count))
End With

'Calculate step-value for making intermediate numbers
k = UBound(SrcList, 1)
i = LBound(SrcList, 1)
step = SrcList(i, 1) - SrcList(k, 1)
step = (step / (k - 1) * -1)

Rslt(1) = SrcList(1, 1) 'First cell value copied
Rslt(k) = SrcList(k, 1) ' Last cell value copied

k = 1

For i = 2 To (UBound(Rslt) - 1) 'Step value applied to cells 2 - n
Rslt(i) = Rslt(k) + step
k = i
Next i

If myTarg.Rows.Count 1 Then
ConnectTheDots = Application.WorksheetFunction.Transpose(Rslt)
Else
ConnectTheDots = Rslt
End If
End Function

input and output:
41.86 41.86
43.41 39.67
55.13 37.47
46.56 35.27
42.46 33.08
36.47 30.88
33.70 28.68
42.84 26.49
46.86 24.29
22.80 22.09
29.19 19.90
17.70 17.70

"Fredrik Wahlgren" wrote:

Hi

I'm interested in knowing what worksheet functions and commands you feel are
missing in Excel. I have noticed that many people have mede various VBA
functions and commands available that are very useful depending on your
needs. Some of them should perhaps be incorporated in Excel in the future.

one thing that I feel is mssing is documentation on making excel add-ins on
the Mac using acompile language like C.

One of ther reasons I'm asking this is because I'm now learning to make
automation add-ins in C++.

/Fredrik