Emacs 基础offset值
cc-mode有如下规定：
One of the symbols +, -, ++, --, *, or /These special symbols describe a relative offset in multiples of c-basic-offset:
By
defining a style's indentation in terms of c-basic-offset, you can
change the amount of whitespace given to an indentation level while
maintaining the same basic shape of your code. Here are the values that
the special symbols correspond to:
+ c-basic-offset times 1
- c-basic-offset times -1
++ c-basic-offset times 2
-- c-basic-offset times -2
* c-basic-offset times 0.5
/ c-basic-offset times -0.5
