Document Classes ⇒ referencing a post calculated value...

[GuntherReissig]

This is a follow up question to https://latex.org/forum/viewtopic.php?t=20826.

I would like to modify the solution proposed by cgnieder (Tue Jul 03, 2012 11:09 pm) so that I can use the result of \getlastvalue{mycounter} further. I would like to be able to assign this number to a counter, and to use it to define the number of columns in a table as in \begin{tabular}{*\getlastvalue{mycounter}{c}} ... and so on.

How to do that?