31.3.5 Customizing C Indentation
C mode and related modes use a flexible mechanism for customizing
indentation. C mode indents a source line in two steps: first it
classifies the line syntactically according to its contents and
context; second, it determines the indentation offset associated by
your selected style with the syntactic construct and adds this
onto the indentation of the anchor statement.
- C-c . <RET> style <RET>
- Select a predefined style style (
A style is a named collection of customizations that can be
used in C mode and the related modes. Styles, for a complete description. Emacs comes with several
predefined styles, including
awk. Some of these
styles are primarily intended for one language, but any of them can be
used with any of the languages supported by these modes. To find out
what a style looks like, select it and reindent some code, e.g., by
typing <C-M-q> at the start of a function definition.
To choose a style for the current buffer, use the command C-c
.. Specify a style name as an argument (case is not significant).
This command affects the current buffer only, and it affects only
future invocations of the indentation commands; it does not reindent
the code already in the buffer. To reindent the whole buffer in the
new style, you can type C-x h C-M-\.
You can also set the variable
c-default-style to specify the
default style for various major modes. Its value should be either the
style's name (a string) or an alist, in which each element specifies
one major mode and which indentation style to use for it. For
'((java-mode . "java") (awk-mode . "awk") (other . "gnu")))
specifies explicit choices for Java and AWK modes, and the default
‘gnu’ style for the other C-like modes. (These settings are
actually the defaults.) This variable takes effect when you select
one of the C-like major modes; thus, if you specify a new default
style for Java mode, you can make it take effect in an existing Java
mode buffer by typing M-x java-mode there.
gnu style specifies the formatting recommended by the GNU
Project for C; it is the default, so as to encourage use of our
See Indentation Engine Basics, and
Customizing Indentation, for more
information on customizing indentation for C and related modes,
including how to override parts of an existing style and how to define
your own styles.