How to autocomplete a table?

Question

C++ / C#

Tell me how to make the table autocomplete with symbols?
I have a table with three sections where the width changes depending on the text entered.
In the first section, the text is centered.
In the second section, autocomplete with interleaved characters: the first line is "+ + + + + + +" (first a plus, then a space), the second line is "+ + + + + + +" (first a space, then a plus), etc. . to the end of the section.
The third section is crossed out with a cross.

I don’t understand how to make the second and third sections with symbols. Tell me please.