Function: column-number-mode

Toggle column number display in the mode line (Column Number mode).
With a prefix argument ARG, enable Column Number mode if ARG is
positive, and disable it otherwise.

If called from Lisp, enable the mode if ARG is omitted or nil.

Variable: column-number-mode

Non-nil if Column-Number mode is enabled.
See the command `column-number-mode' for a description of this minor mode.