Variable: current-prefix-arg
current-prefix-arg is a variable defined in callint.c.
Value
nil
Documentation
The value of the prefix argument for this editing command.
It may be a number, or the symbol - for just a minus sign as arg,
or a list whose car is a number for just one or more C-u's
or nil if no argument has been specified.
This is what (interactive "P") returns.
Source Code
// Defined in /usr/src/emacs/src/callint.c
DEFVAR_LISP ("current-prefix-arg", Vcurrent_prefix_arg,
doc: /* The value of the prefix argument for this editing command.
It may be a number, or the symbol `-' for just a minus sign as arg,
or a list whose car is a number for just one or more C-u's
or nil if no argument has been specified.
This is what `(interactive \"P\")' returns. */);