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9.1.2 @code
{sample-code}
Use the @code
command to indicate text that is a piece of a
program and which consists of entire syntactic tokens. Enclose the
text in braces.
Thus, you should use @code
for an expression in a program, for
the name of a variable or function used in a program, or for a
keyword in a programming language.
Use @code
for command names in languages that resemble
programming languages, such as Texinfo. For example, @code
and
@samp
are produced by writing ‘@code{@@code}’ and
‘@code{@@samp}’ in the Texinfo source, respectively.
It is incorrect to alter the case of a word inside an @code
command when it appears at the beginning of a sentence. Most computer
languages are case sensitive. In C, for example, Printf
is
different from the identifier printf
, and most likely is a
misspelling of it. Even in languages which are not case sensitive, it
is confusing to a human reader to see identifiers spelled in different
ways. Pick one spelling and always use that. If you do not want to
start a sentence with a command name written all in lowercase, you
should rearrange the sentence.
In the Info output, @code
results in single quotation marks
around the text. In other formats, @code
argument is typeset
in a typewriter (monospace) font. For example,
The function returns @code{nil}.
produces this:
The function returns
nil
.
Here are some cases for which it is preferable not to use @code
:
-
For shell command names such as
ls
(use@command
). -
For environment variable such as
TEXINPUTS
(use@env
). -
For shell options such as ‘-c’ when such options stand alone (use
@option
). -
An entire shell command often looks better if written using
@samp
rather than@code
. In this case, the rule is to choose the more pleasing format. -
For a string of characters shorter than a syntactic token. For example,
if you are writing about ‘goto-ch’, which is just a part of the
name for the
goto-char
Emacs Lisp function, you should use@samp
. -
In general, when writing about the characters used in a token; for
example, do not use
@code
when you are explaining what letters or printable symbols can be used in the names of functions. (Use@samp
.) Also, you should not use@code
to mark text that is considered input to programs unless the input is written in a language that is like a programming language. For example, you should not use@code
for the keystroke commands of GNU Emacs (use@kbd
instead) although you may use@code
for the names of the Emacs Lisp functions that the keystroke commands invoke.
By default, TeX will consider breaking lines at ‘-’ and
‘_’ characters within @code
and related commands. This
can be controlled with @allowcodebreaks
(see section @allowcodebreaks
: Control Line Breaks in @code
). The HTML output attempts to
respect this for ‘-’, but ultimately it is up to the browser’s
behavior. For Info, it seems better never to make such breaks.
For Info, the quotes are omitted in the output of the @code
command and related commands (e.g., @kbd
, @command
),
in typewriter-like contexts such as the @example
environment
(see section @example
: Example Text) and @code
itself, etc.
To control which quoting characters are implicitly inserted by Texinfo
processors in the output of ‘@code’, etc., see the
OPEN_QUOTE_SYMBOL
and CLOSE_QUOTE_SYMBOL
customization
variables (see section Other Customization Variables). This is separate
from how actual quotation characters in the input document are handled
(see section Inserting Quote Characters).
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